Channel quality feedback method and apparatus

ABSTRACT

This application discloses a channel quality feedback method and apparatus, and the channel quality feedback method includes the following steps: determining, by a network device, a channel quality indicator set of a terminal device, where the channel quality indicator set includes at least one channel quality indicator value, and the channel quality indicator value is used to indicate channel quality; and sending, by the network device, the channel quality indicator set to the terminal device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation application of InternationalApplication No. PCT/CN2018/091681, filed on Jun. 15, 2018, which claimspriority to Chinese Patent Application No. 201710459701.5, filed on Jun.16, 2017 and claims priority to Chinese Patent Application No.201710687964.1, filed on Aug. 11, 2017. The disclosures of theaforementioned applications are hereby incorporated by reference intheir entireties.

TECHNICAL FIELD

This application relates to the field of communications technologies,and in particular, to a channel quality feedback method and apparatus.

BACKGROUND

Compared with a 4G communications system, a 5G communications systemsupports an ultra-reliable and low latency communications (URLLC)service. The URLLC service needs to meet a strict reliabilityrequirement in a harsh transmission latency condition. However, robustreduction of a modulation and coding level only leads to low systemtransmission efficiency. Therefore, a channel quality informationfeedback needs to be enhanced to enable a network device to performtransmission by using a modulation and coding scheme that is mostsuitable for current channel quality, so that not only transmissionreliability can be ensured, but also scheduling with excessively lowtransmission efficiency can be avoided.

For example, a channel quality indicator (CQI) is a typical feedbacktechnology of channel quality information. In an LTE system, each CQIindex corresponds to one modulation and coding policy of specificchannel quality. After learning of a CQI index corresponding to currentchannel quality, the network device can perform transmission by using amodulation and coding policy corresponding to the CQI index. Currently,there are two manners of feeding back a CQI index in the industry: anabsolute indicator value feedback and a differential indicator valuefeedback. In the absolute indicator value feedback, after obtaining thecurrent channel quality through measurement, a terminal device feedsback one type of feedback information, and the feedback informationcorresponds to the CQI index corresponding to the current channelquality. In other words, one type of feedback information corresponds toone type of CQI index. For example, if 16 types of CQI indexes areincluded, four-bit feedback information needs to be used for a feedback.Usually, limited types of CQI indexes are set to reduce overheads, andonly typical channel quality states can be reflected, but channelquality cannot be accurately reflected for a deep fading channel.

In the differential indicator value feedback, a CQI reference indexvalue is first determined, and an offset is calculated for eachremaining CQI index by using the reference index value as a reference.Therefore, the terminal device only needs to feed back feedbackinformation corresponding to the offset. To reduce overheads of feedbackinformation, several optional offsets are determined to form a CQIdifferential indicator value set, and one type of feedback informationcorresponds to one offset. For example, a CQI differential indicatorvalue set is {−1, 0, 1, 2}. The terminal device may feed back the fouroffsets by using two-bit feedback information. Currently, the CQIdifferential indicator value set is specified for all cases in theindustry. For example, when an offset is 2, feedback information fedback by the terminal device is 11, and when an offset is 5, the feedbackinformation fed back by the terminal device is still 11. Therefore, theterminal device cannot accurately indicate current channel quality of achannel.

It may be learned from the foregoing description that in the currentsystem, channel quality of each terminal cannot be accurately indicatedregardless of whether an absolute indicator value or a differentialindicator value is used.

SUMMARY

Embodiments of this application provide a channel quality feedbackmethod and apparatus, to determine a channel quality indicator setexclusive to a terminal device, so that not only overheads are reduced,but also accuracy of a channel quality feedback can be maximized.

According to a first aspect, an embodiment of this application providesa channel quality feedback method, including: determining, by a networkdevice, a channel quality indicator set of a terminal device. Thechannel quality indicator set includes a channel quality indicatorvalue, and the channel quality indicator value is used to indicatechannel quality. Optionally, the channel quality indicator set mayinclude at least one channel quality indicator value.

The network device sends the determined channel quality indicator set tothe terminal device. Optionally, the network device may indicate thechannel quality indicator set by using a higher layer signalingconfiguration, or the network device may indicate the channel qualityindicator set by using MAC CE signaling. Further, the channel qualityindicator set may be alternatively indicated by using user-specificsignaling.

In a possible design, the network device sends, to the terminal device,an indication message that is used to indicate the channel qualityindicator set, where the indication message includes the at least onechannel quality indicator value.

In a possible design, the channel quality indicator value may include achannel quality differential indicator value, and the channel qualitydifferential indicator value is used to indicate an offset between achannel quality measurement value and a channel quality reference value.For example, the channel quality measurement value is a CQI indexobtained through measurement, and the channel quality reference value isa CQI reference index value. It should be noted that the channel qualityherein includes but is not limited to a CQI, an MCS, and a BLER.

In a possible design, the channel quality reference value includes achannel quality value that is aperiodically fed back at a time closestto a reference time corresponding to the measurement value; or a channelquality value that is periodically fed back at a time closest to areference time corresponding to the measurement value; or a channelquality value that is fed back at a time closest to a reference timecorresponding to the measurement value and that is in a specific channelquality reporting set, where the reference time corresponding to themeasurement value includes a reference measurement time corresponding tothe measurement value or a measurement reporting time corresponding tothe measurement value, the measurement reporting time corresponding tothe measurement value is a time for sending feedback information of themeasurement value by the terminal device, the feedback information ischannel quality information fed back by the terminal device for thechannel quality indicator set, and the reference measurement time is apreset time period before the measurement reporting time.

In a possible design, the network device determines a first channelquality indicator set and a second channel quality indicator set for theterminal device, where the first channel quality indicator setcorresponds to an interval of a first time period, and the secondchannel quality indicator set corresponds to an interval of a secondtime period. The interval of the first time period and the interval ofthe second time period may be intervals of any two time periods ofintervals that are of a plurality of time periods and that aredetermined by the network device for the terminal device, and theintervals of the plurality of time periods do not overlap. The networkdevice sends, to the terminal device, a plurality of channel qualityindicator sets corresponding to the determined intervals of theplurality of time periods.

In a possible design, the network device receives the feedbackinformation sent by the terminal device, where the feedback informationis used to indicate a target differential indicator value in a firsttarget channel quality indicator set, the first target channel qualityindicator set is a channel quality indicator set corresponding to a timedifference between the reference time corresponding to the measurementvalue and a reference time corresponding to the reference value, thetarget differential indicator value is used to indicate an offsetbetween a current channel quality measurement value and a channelquality reference value, and the first target channel quality indicatorset is the first channel quality indicator set or the second channelquality indicator set.

In a possible design, the network device determines a third channelquality indicator set and a fourth channel quality indicator set for theterminal device, where the third channel quality indicator setcorresponds to an interval of a third block error rate difference, andthe fourth channel quality indicator set corresponds to an interval of afourth block error rate difference. The interval of the third blockerror rate difference and the interval of the fourth block error ratedifference may be intervals of any two block error rate differences ofintervals that are of a plurality of block error rate differences andthat are determined by the network device for the terminal device, andthe intervals of the plurality of block error rate differences do notoverlap. The network device sends, to the terminal device, a pluralityof channel quality indicator sets corresponding to the determinedintervals of the plurality of block error rate differences.

In a possible design, the network device receives feedback informationsent by the terminal device, where the feedback information is used toindicate a target differential indicator value in a second targetchannel quality indicator set, the second target channel qualityindicator set is a channel quality indicator set corresponding to adifference between a block error rate corresponding to the measurementvalue and a block error rate corresponding to the reference value, thetarget differential indicator value is used to indicate an offsetbetween a current channel quality measurement value and a channelquality reference value, and the second target channel quality indicatorset is the third channel quality indicator set or the fourth channelquality indicator set.

In a possible design, the channel quality indicator value in the channelquality indicator set includes a channel quality absolute indicatorvalue, and the absolute indicator value is used to indicate a channelquality measurement value. For example, the absolute indicator value isa CQI index.

Optionally, the channel quality indicator set determined by the networkdevice for the terminal device is a preset set or a subset of the presetset. The preset set may be a set specified in a protocol, namely, a setpreset in the network device and the terminal device. A quantity ofabsolute indicator values included in the preset set is greater than orequal to a quantity of absolute indicator values included in the channelquality indicator set determined by the network device for the terminaldevice. The quantity of absolute indicator values included in thechannel quality indicator set determined by the network device for theterminal device determines a quantity of bits required by the terminaldevice to send the feedback information to the network device. Forexample, if the quantity of absolute indicator values included in thechannel quality indicator set determined by the network device for theterminal device is 16, the quantity of bits required for the feedbackinformation is 4. In this way, absolute indicator values included in thechannel quality indicator set exclusive to the terminal device can befed back by using a limited quantity of bits for the feedbackinformation, so that a feedback is more accurate. Quantities of absoluteindicator values included in channel quality indicator sets determinedby the network device for different terminal devices may be different,and therefore quantities of bits required by the terminal devices tosend feedback information to the network device may also be different.

Optionally, absolute indicator values included in the channel qualityindicator set determined by the network device for the terminal devicemay be consecutively selected or may be nonconsecutively selected fromthe preset set. If the absolute indicator values included in the channelquality indicator set are consecutively selected or the absoluteindicator values included in the channel quality indicator set areselected at equal intervals, when indicating the channel qualityindicator set to the terminal device, the network device may indicateonly a starting element of the channel quality indicator set and aquantity of elements included in the channel quality indicator set, orthe network device indicates only a starting element, and a quantity ofelements included in the channel quality indicator set is a valuespecified in the protocol. It should be noted that consecutive selectionherein may be successive selection based on a sequence number of theabsolute indicator values.

Optionally, if the absolute indicator values included in the channelquality indicator set are nonconsecutively selected and there is novalue selection rule, the network device may indicate the channelquality indicator set to the terminal device by using a bitmap, or thenetwork device separately indicates indices corresponding to absoluteindicator values in the preset set.

Optionally, absolute indicator values included in the channel qualityindicator set determined by the network device for the terminal devicemay be some or all of channel quality indicator values in at least oneof a plurality of preset sets. Optionally, at least two of the pluralityof preset sets include different quantities of absolute indicatorvalues. It should be noted that the preset set may be a set preset inthe network device and the terminal device.

According to a second aspect, an embodiment of this application providesa network device, and the network device has a function of implementingbehavior of the network device in the method in the first aspect. Thefunction may be implemented by hardware, or may be implemented byhardware executing corresponding software. The hardware or the softwareincludes one or more modules corresponding to the function.

In a possible implementation, the network device includes a processingunit and a transceiver unit. The processing unit is configured todetermine a channel quality indicator set of a terminal device, wherethe channel quality indicator set includes at least one channel qualityindicator value, and the channel quality indicator value is used toindicate channel quality. The transceiver unit is configured to send thechannel quality indicator set to the terminal device.

In a possible implementation, the network device includes a processorand a transceiver. The processor is configured to determine a channelquality indicator set of a terminal device, where the channel qualityindicator set includes at least one channel quality indicator value, andthe channel quality indicator value is used to indicate channel quality.The transceiver is configured to send the channel quality indicator setto the terminal device.

Based on a same inventive concept, for a problem-resolving principle andbeneficial effects of the network device, refer to the method in thefirst aspect and beneficial effects brought by the method. Forimplementation of the network device, refer to implementation of themethod on the network device side in the first aspect. Details are notdescribed again.

According to a third aspect, an embodiment of this application providesa channel quality feedback method, including: obtaining, by a terminaldevice, a channel quality indicator set determined by a network devicefor the terminal device, where the channel quality indicator setincludes at least one channel quality indicator value, and the channelquality indicator value is used to indicate channel quality; andsending, by the terminal device, feedback information to the networkdevice, where the feedback information is used to indicate a targetchannel quality indicator value, the target channel quality indicatorvalue is a channel quality indicator value in the channel qualityindicator set, and the target channel quality indicator value is used todetermine current channel quality of a channel.

In a possible design, the channel quality indicator value includes achannel quality differential indicator value, and the differentialindicator value is used to indicate an offset between a channel qualitymeasurement value and a channel quality reference value.

In a possible design, the channel quality reference value includes: achannel quality value that is aperiodically fed back at a time closestto a measurement time corresponding to the measurement value; or achannel quality value that is periodically fed back at a time closest toa measurement time corresponding to the measurement value; or a channelquality value that is fed back at a time closest to a measurement timecorresponding to the measurement value and that is in a specific channelquality reporting set.

In a possible design, the obtaining, by a terminal device, a channelquality indicator set determined by a network device for the terminaldevice includes: obtaining, by the terminal device, a first channelquality indicator set and a second channel quality indicator set, wherethe first channel quality indicator set corresponds to an interval of afirst time period, the second channel quality indicator set correspondsto an interval of a second time period, the first time period or thesecond time period is a time difference between a reference timecorresponding to the measurement value and a reference timecorresponding to the reference value, and the interval of the first timeperiod is different from the interval of the second time period; and thesending, by the terminal device, feedback information to the networkdevice includes: determining, by the terminal device, a first targetdifferential set, where the first target differential set is a channelquality indicator set corresponding to a time difference between themeasurement time corresponding to the channel quality measurement valueand a feedback time corresponding to the channel quality referencevalue, and the first target differential set is the first channelquality indicator set or the second channel quality indicator set; andsending, by the terminal device to the network device, feedbackinformation used to indicate a target differential indicator value inthe first target differential set.

In a possible design, the obtaining, by a terminal device, a channelquality indicator set determined by a network device for the terminaldevice includes: obtaining, by the terminal device, a third channelquality indicator set and a fourth channel quality indicator set, wherethe third channel quality indicator set corresponds to an interval of athird block error rate difference, the fourth channel quality indicatorset corresponds to an interval of a fourth block error rate difference,the third block error rate difference or the fourth block error ratedifference is a difference between a block error rate corresponding tothe channel quality measurement value and a block error ratecorresponding to the channel quality reference value, and the intervalof the third block error rate difference is different from the intervalof the fourth block error rate difference; and the sending, by theterminal device, feedback information to the network device includes:determining, by the terminal device, a second target differential set,where the second target differential set is a channel quality indicatorset corresponding to the difference between the block error ratecorresponding to the channel quality measurement value and the blockerror rate corresponding to the channel quality reference value, and thesecond target differential set is the third channel quality indicatorset or the fourth channel quality indicator set; and sending, by theterminal device to the network device, feedback information used toindicate a target differential indicator value in the second targetdifferential set.

In a possible design, the channel quality indicator value includes achannel quality absolute indicator value, and the absolute indicatorvalue is used to indicate a channel quality measurement value; and thechannel quality indicator set is a preset set or a subset of the presetset, or the channel quality set is at least one of a plurality of presetsets.

Optionally, the channel quality indicator set determined by the networkdevice for the terminal device is a preset set or a subset of the presetset. The preset set may be a set specified in a protocol, namely, a setpreset in the network device and the terminal device.

Optionally, absolute indicator values included in the channel qualityindicator set determined by the network device for the terminal devicemay be consecutively selected from the preset set, or absolute indicatorvalues included in the channel quality indicator set may benonconsecutively selected from the preset set.

Optionally, absolute indicator values included in the channel qualityindicator set determined by the network device for the terminal devicemay be some or all of channel quality indicator values in the at leastone of the plurality of preset sets. The plurality of preset sets may besets preset in the network device and the terminal device.

According to a fourth aspect, an embodiment of this application providesa terminal device, and the terminal device has a function ofimplementing behavior of the terminal device in the method in the thirdaspect. The function may be implemented by hardware, or may beimplemented by hardware executing corresponding software. The hardwareor the software includes one or more modules corresponding to thefunction.

In a possible implementation, the terminal device includes a transceiverunit and a processing unit. The processing unit is configured to obtaina channel quality indicator set determined by a network device for theterminal device, where the channel quality indicator set includes atleast one channel quality indicator value, and the channel qualityindicator value is used to indicate channel quality.

The transceiver unit is configured to send feedback information, wherethe feedback information is used to indicate a target channel qualityindicator value, the target channel quality indicator value is a channelquality indicator value in the channel quality indicator set, and thetarget channel quality indicator value is used to determine currentchannel quality of a channel.

In a possible implementation, the terminal device includes a processorand a transceiver. The processor is configured to obtain a channelquality indicator set determined by a network device for the terminaldevice, where the channel quality indicator set includes at least onechannel quality indicator value, and the channel quality indicator valueis used to indicate channel quality.

The transceiver is configured to send feedback information, where thefeedback information is used to indicate a target channel qualityindicator value, the target channel quality indicator value is a channelquality indicator value in the channel quality indicator set, and thetarget channel quality indicator value is used to determine currentchannel quality of a channel.

Based on a same inventive concept, for a problem-resolving principle andbeneficial effects of the terminal device, refer to the method in thethird aspect and beneficial effects brought by the method. Forimplementation of the terminal device, refer to implementation of themethod on the terminal device side in the third aspect. Details are notdescribed again.

According to a fifth aspect, an embodiment of this application providesa modulation and coding policy indication method, including:determining, by a network device, a modulation and coding scheme MCSlevel indicator set of a terminal device, where the MCS level indicatorset includes an MCS level indicator value, and the MCS level indicatorvalue is used to indicate a modulation and coding policy; and sending,by the network device, the MCS level indicator set to the terminaldevice.

In a possible implementation, the network device sends indicationinformation to the terminal device, where the indication information isused to indicate a target MCS level indicator value in the MCS levelindicator set, and the target MCS level indicator value is used toindicate a modulation and coding policy used by the network device.

In a possible implementation, the MCS level indicator set is a presetset or a subset of the preset set, or the MCS level indicator set is atleast one of a plurality of preset sets.

Optionally, the MCS level indicator set determined by the network devicefor the terminal device is a preset set or a subset of the preset set.The preset set may be a set specified in a protocol, namely, a setpreset in the network device and the terminal device.

Optionally, MCS level indicator values included in the MCS levelindicator set determined by the network device for the terminal devicemay be consecutively selected from the preset set, or MCS levelindicator values included in the MCS level indicator set may benonconsecutively selected from the preset set.

If the MCS level indicator values included in the MCS level indicatorset are consecutively selected from the preset set, or the MCS levelindicator values included in the MCS level indicator set are selected atequal intervals, when indicating the MCS level indicator set to theterminal device, the network device may indicate only a starting elementof the MCS level indicator set and a quantity of elements included inthe MCS level indicator set, or the network device indicates only astarting element, and a quantity of elements included in the MCS levelindicator set is a value specified in the protocol.

Optionally, if the MCS level indicator values included in the MCS levelindicator set are nonconsecutively selected from the preset set andthere is no value selection rule, the network device may indicate theMCS level indicator set to the terminal device by using a bitmap.

Optionally, MCS level indicator values included in the MCS levelindicator set determined by the network device for the terminal devicemay be some or all of MCS level indicator values in the at least one ofthe plurality of preset sets. The plurality of preset sets may be setspreset in the network device and the terminal device.

According to a sixth aspect, an embodiment of this application providesa network device, and the network device has a function of implementingbehavior of the network device in the method in the fifth aspect. Thefunction may be implemented by hardware, or may be implemented byhardware executing corresponding software. The hardware or the softwareincludes one or more modules corresponding to the function.

In a possible implementation, the network device includes a processingunit and a transceiver unit. The processing unit is configured todetermine a modulation and coding scheme MCS level indicator set of aterminal device, where the MCS level indicator set includes an MCS levelindicator value, and the MCS level indicator value is used to indicate amodulation and coding policy.

The transceiver unit is configured to send the MCS level indicator setto the terminal device.

In a possible implementation, the network device includes a processorand a transceiver. The processor is configured to determine a modulationand coding scheme MCS level indicator set of a terminal device, wherethe MCS level indicator set includes an MCS level indicator value, andthe MCS level indicator value is used to indicate a modulation andcoding policy.

The transceiver is configured to send the MCS level indicator set to theterminal device.

Based on a same inventive concept, for a problem-resolving principle andbeneficial effects of the network device, refer to the method in thefifth aspect and beneficial effects brought by the method. Forimplementation of the network device, refer to implementation of themethod on the network device side in the fifth aspect. Details are notdescribed again.

According to a seventh aspect, an embodiment of this applicationprovides a modulation and coding policy indication method, including:receiving, by a terminal device, an MCS level indicator set determinedfor the terminal device, where the MCS level indicator set includes atleast one MCS level indicator value, and the MCS level indicator valueis used to indicate a modulation and coding policy; and storing, by theterminal device, the MCS level indicator set.

In a possible implementation, the terminal device receives indicationinformation sent by a network device, where the indication informationis used to indicate a target MCS level indicator value in the MCS levelindicator set, and the target MCS level indicator value is used toindicate a modulation and coding policy used by the network device.

In a possible implementation, the MCS level indicator set is a presetset or a subset of the preset set, or the MCS level indicator set is oneof a plurality of preset sets.

According to an eighth aspect, an embodiment of this applicationprovides a terminal device, and the terminal device has a function ofimplementing behavior of the terminal device in the method in theseventh aspect. The function may be implemented by hardware, or may beimplemented by hardware executing corresponding software. The hardwareor the software includes one or more modules corresponding to thefunction.

In a possible implementation, the terminal device includes a transceiverunit and a processing unit. The transceiver unit is configured toreceive an MCS level indicator set determined for the terminal device,where the MCS level indicator set includes an MCS level indicator value,and the MCS level indicator value is used to indicate a modulation andcoding policy.

The processing unit is configured to store the MCS level indicator set.

In a possible implementation, the terminal device includes a processorand a transceiver. The transceiver is configured to receive an MCS levelindicator set determined for the terminal device, where the MCS levelindicator set includes an MCS level indicator value, and the MCS levelindicator value is used to indicate a modulation and coding policy.

The processor is further configured to store the MCS level indicatorset.

Based on a same inventive concept, for a problem-resolving principle andbeneficial effects of the terminal device, refer to the method in theseventh aspect and beneficial effects brought by the method. Forimplementation of the terminal device, refer to implementation of themethod on the terminal device side in the seventh aspect. Details arenot described again.

According to a ninth aspect, an embodiment of this application providesa computer readable storage medium, including an instruction. When theinstruction runs on a computer, the computer is enabled to perform themethod performed by the network device in the first aspect.

According to a tenth aspect, an embodiment of this application providesa computer readable storage medium, including an instruction. When theinstruction runs on a computer, the computer is enabled to perform themethod on the terminal device side in the third aspect.

According to an eleventh aspect, an embodiment of this applicationprovides a computer readable storage medium, including an instruction.When the instruction runs on a computer, the computer is enabled toperform the method performed by the network device in the fifth aspect.

According to a twelfth aspect, an embodiment of this applicationprovides a computer readable storage medium, including an instruction.When the instruction runs on a computer, the computer is enabled toperform the method on the terminal device side in the seventh aspect.

In the embodiments of this application, the network device configures achannel quality indicator set exclusive to each terminal device for theterminal device, where the channel quality indicator set includes achannel quality indicator value, the channel quality indicator value isused to indicate channel quality, and the channel quality indicatorvalue is set for channel quality of the terminal device. Therefore, whenfeeding back the channel quality, the terminal device can accuratelyfeed back the channel quality to the network device, thereby improvingaccuracy of a channel quality feedback.

According to a thirteenth aspect, an embodiment of this applicationprovides a method for determining channel quality. The method is appliedto a system that supports at least one block error rate BLER set, afirst BLER set of the at least one BLER set includes a first BLER subsetand a second BLER subset, the first BLER subset includes at least oneBLER, the second BLER subset includes at least one BLER, and the methodincludes: receiving, by a network device, a channel quality parameterthat corresponds to each BLER in the first BLER subset and that is sentby a terminal device, where the channel quality parameter is used toindicate channel quality between the terminal device and the networkdevice; and determining, by the network device based on at least onechannel quality parameter difference and a channel quality parametercorresponding to the at least one BLER in the first BLER subset, achannel quality parameter corresponding to the at least one BLER in thesecond BLER subset, where the at least one channel quality parameterdifference includes a difference between the channel quality parametercorresponding to the at least one BLER in the second BLER subset and thechannel quality parameter corresponding to the at least one BLER in thefirst BLER subset.

The network device may receive a channel quality parameter thatcorresponds to a BLER in the first BLER subset in the first BLER set andthat is sent by the terminal device, and determine, based on channelquality parameters corresponding to some BLERs in the first BLER subsetand the channel quality parameter difference between the channel qualityparameter corresponding to each BLER in the second BLER subset and thechannel quality parameter corresponding to the at least one BLER in thefirst BLER subset, channel quality parameters corresponding to all BLERsin the second BLER subset. In other words, the network device candetermine channel quality parameters corresponding to all BLERs in thefirst BLER set, and therefore the terminal device does not need to sendthe channel quality parameters corresponding to all the BLERs in thefirst BLER set, thereby reducing signaling overheads.

In a possible implementation, the method further includes: sending, bythe network device, a channel quality parameter request to the terminaldevice, where the channel quality parameter request is used to requestthe at least one channel quality parameter difference between thechannel quality parameter corresponding to the at least one BLER in thesecond BLER subset in the first BLER set and the channel qualityparameter corresponding to the at least one BLER in the first BLERsubset in the first BLER set; and receiving, by the network device, theat least one channel quality parameter difference between the channelquality parameter corresponding to the at least one BLER in the secondBLER subset in the first BLER set and the channel quality parametercorresponding to the at least one BLER in the first BLER subset in thefirst BLER set.

When the network device requires the channel quality parameterdifference, the network device sends the channel quality parameterrequest to the terminal device, and requests, by using the channelquality parameter request, the channel quality parameter differencerequired by the network device, so that the terminal device is preventedfrom reporting an extra channel quality parameter difference, therebyfurther reducing signaling overheads.

In a possible implementation, the method further includes: sending, bythe network device, a channel quality parameter request to the terminaldevice, where the channel quality parameter request is used to request achannel quality parameter difference between a channel quality parametercorresponding to at least one BLER in a second BLER subset in each ofthe at least one BLER set and a channel quality parameter correspondingto at least one BLER in a first BLER subset; and receiving, by thenetwork device, the channel quality parameter difference between thechannel quality parameter corresponding to the at least one BLER in thesecond BLER subset in each of the at least one BLER set and the channelquality parameter corresponding to the at least one BLER in the firstBLER subset.

The network device may request all channel quality parameter differencesto determine channel quality parameters corresponding to all BLERs,thereby improving reliability of channel quality.

In a possible implementation, if the method is applied to a system thatsupports at least two BLER sets, any two of the at least two BLER setscorrespond to different CQI levels.

The network device may receive channel quality parameter differencesbetween channel quality parameters corresponding to BLERs in differentCQI levels reported by the terminal device, thereby improving accuracyof determining a channel quality parameter corresponding to a BLER inthe second BLER subset.

In a possible implementation, if the method is applied to a system thatsupports at least two BLER sets, any two of the at least two BLER setscorrespond to different transmission modes.

The network device may receive channel quality parameter differencesbetween channel quality parameters corresponding to BLERs in differenttransmission modes reported by the terminal device, thereby improvingaccuracy of determining a channel quality parameter corresponding to aBLER in the second BLER subset.

In a possible implementation, the transmission modes include an antennaport configuration and/or a multiple-input multiple-output MIMOpreprocessing mode.

The network device may receive channel quality parameter differencesbetween channel quality parameters corresponding to BLERs in differentantenna port configurations and/or multiple-input multiple-output MIMOpreprocessing modes reported by the terminal device, thereby furtherimproving accuracy of determining a channel quality parametercorresponding to a BLER in the second BLER subset.

According to a fourteenth aspect, a method for determining channelquality is provided. The method is applied to a system that supports atleast one block error rate BLER set, each of the at least one BLER setincludes a first BLER subset and a second BLER subset, the first BLERsubset includes at least one BLER, the second BLER subset includes atleast one BLER, and the method includes: determining, by a terminaldevice, a channel quality parameter corresponding to each BLER in thefirst BLER subset, where the channel quality parameter is used toindicate channel quality between the terminal device and a networkdevice; and sending, by the terminal device, the channel qualityparameter corresponding to each BLER in the first BLER subset to thenetwork device, so that the network device determines, based on at leastone channel quality parameter difference and a channel quality parametercorresponding to the at least one BLER in the first BLER subset, achannel quality parameter corresponding to the at least one BLER in thesecond BLER subset, where the at least one channel quality parameterdifference includes a difference between the channel quality parametercorresponding to the at least one BLER in the second BLER subset and thechannel quality parameter corresponding to the at least one BLER in thefirst BLER subset.

The terminal device sends a channel quality parameter corresponding toeach BLER in a first BLER subset in a first BLER set, and determines,based on channel quality parameters corresponding to some BLERs in thefirst BLER subset and the channel quality parameter difference betweenthe channel quality parameter corresponding to each BLER in the secondBLER subset and the channel quality parameter corresponding to the atleast one BLER in the first BLER subset, channel quality parameterscorresponding to all BLERs in the second BLER subset. In other words,the network device can determine channel quality parameterscorresponding to all BLERs in the first BLER set, and therefore theterminal device does not need to send the channel quality parameterscorresponding to all the BLERs in the first BLER set, thereby reducingsignaling overheads.

In some possible implementations, the method further includes:receiving, by the terminal device, a channel quality parameter requestsent by the network device, where the channel quality parameter requestis used to request at least one channel quality parameter differencebetween a channel quality parameter corresponding to at least one BLERin a second BLER subset in the first BLER set and a channel qualityparameter corresponding to at least one BLER in a first BLER subset inthe first BLER set; and sending, by the terminal device, the at leastone channel quality parameter difference between the channel qualityparameter corresponding to the at least one BLER in the second BLERsubset in the first BLER set and the channel quality parametercorresponding to the at least one BLER in the first BLER subset in thefirst BLER set to the network device according to the channel qualityparameter request.

The terminal device receives the channel quality parameter request sentby the network device to the terminal device when the network devicerequires the channel quality parameter difference, and feeds back thechannel quality parameter difference required by the network device, sothat the terminal device is prevented from reporting an extra channelquality parameter difference, thereby further reducing signalingoverheads.

In some possible implementations, the method further includes:receiving, by the terminal device, a channel quality parameter requestsent by the network device, where the channel quality parameter requestis used to request the channel quality parameter difference between thechannel quality parameter corresponding to the at least one BLER in thesecond BLER subset in each of the at least one BLER set and the channelquality parameter corresponding to the at least one BLER in the firstBLER subset; and sending, by the terminal device, the channel qualityparameter difference between the channel quality parameter correspondingto the at least one BLER in the second BLER subset in each of the atleast one BLER set and the channel quality parameter corresponding tothe at least one BLER in the first BLER subset to the network deviceaccording to the channel quality parameter request.

The terminal device may send, to the network device, all channel qualityparameter differences requested by the network device, to determinechannel quality parameters corresponding to all BLERs, thereby improvingreliability of channel quality.

In some possible implementations, the method further includes: if themethod is applied to a system that supports at least two BLER sets, anytwo of the at least two BLER sets correspond to different CQI levels.

The terminal device may send, to the network device, channel qualityparameter differences between channel quality parameters correspondingto BLERs in different CQI levels requested by the network device,thereby improving accuracy of determining a channel quality parametercorresponding to a BLER in the second BLER subset.

In some possible implementations, if the method is applied to a systemthat supports at least two BLER sets, any two of the at least two BLERsets correspond to different transmission modes.

The terminal device may send, to the network device, channel qualityparameter differences between channel quality parameters correspondingto BLERs in different transmission modes requested by the networkdevice, thereby improving accuracy of determining a channel qualityparameter corresponding to a BLER in the second BLER subset.

In some possible implementations, the transmission modes include anantenna port configuration and/or a multiple-input multiple-output MIMOpreprocessing mode.

The terminal device may send, to the network device, channel qualityparameter differences between channel quality parameters correspondingto BLERs in different antenna port configurations and/or multiple-inputmultiple-output MIMO preprocessing modes requested by the networkdevice, thereby further improving accuracy of determining a channelquality parameter corresponding to a BLER in the second BLER subset.

According to a fifteenth aspect, a communication method is provided,including: determining, by a terminal device, indication informationbased on a correspondence table, where the indication information isused to indicate at least one channel quality indicator CQI index, thecorrespondence table includes N CQI indexes, M modulation schemes, and Kcode rate parameters, at least one of the N CQI indexes corresponds toone type of modulation scheme, K of the N CQI indexes are in aone-to-one correspondence with the K code rate parameters, and a productof a code rate corresponding to a first CQI index of the N CQI indexesand a modulation order of a modulation scheme corresponding to the firstCQI index is a value greater than 0 and less than 0.0781, where CodeRate Parameter=Code Rate×1024, N>M, N≥K, and N, K, and M are allpositive integers; and sending, by the terminal device, the indicationinformation to a network device.

In this embodiment of this application, the terminal device determinesthe indication information based on the correspondence table, where theindication information is used to indicate the at least one channelquality indicator CQI index, the correspondence table includes the N CQIindexes, the M modulation schemes, and the K code rate parameters, theat least one of the N CQI indexes corresponds to one type of modulationscheme, the K of the N CQI indexes are in a one-to-one correspondencewith the K code rate parameters, and the product of the code ratecorresponding to the first CQI index of the N CQI indexes and themodulation order of the modulation scheme corresponding to the first CQIindex is a value greater than 0 and less than 0.0781, where Code RateParameter=Code Rate×1024, N>M, N≥K, and N, K, and M are all positiveintegers; and the terminal device sends the indication information, sothat the network device determines, according to the indicationinformation, the modulation scheme corresponding to the at least one CQIindex. In other words, this application can be applied to a system thatrequires spectrum efficiency lower than 0.0781, that is, an area in abad channel condition is covered, to ensure that a user can performcommunication on a deep fading channel.

In a possible implementation, the K code rate parameters include a valuegreater than 0 and less than 40.

In a possible implementation, the N CQI indexes in the correspondencetable are arranged in ascending order, products of modulation orders ofmodulation schemes corresponding to all of the first P CQI indexes ofthe N CQI indexes and code rates corresponding to all of the first P CQIindexes are arranged in ascending order, and a product of a modulationorder of a modulation scheme corresponding to a (P+h)^(th) CQI index anda code rate corresponding to the (P+h)^(th) CQI index is less than aproduct of a modulation order of a modulation scheme corresponding to aP^(th) CQI index and a code rate corresponding to the P^(th) CQI index,where N>P+h, h is a value ranging from 1 to N−X, and X>P.

A spectrum efficiency value less than 0.0781 that corresponds to a CQIindex may be arranged behind a maximum spectrum efficiency value, sothat the terminal device can determine, as required, a quantity of bitsincluded in channel quality indication information.

According to a sixteenth aspect, a communication method is provided,including: receiving, by a network device, indication information, wherethe indication information is used to indicate at least one channelquality indicator CQI index; and determining, by the network devicebased on a correspondence table, a modulation and coding schemecorresponding to the at least one CQI index, where the correspondencetable includes N CQI indexes, M modulation schemes, and K code rateparameters, at least one of the N CQI indexes corresponds to one type ofmodulation scheme, K of the N CQI indexes are in a one-to-onecorrespondence with the K code rate parameters, and a product of a coderate parameter corresponding to a first CQI index of the N CQI indexesand a modulation order of a modulation scheme corresponding to the firstCQI index is a value greater than 0 and less than 0.0781, where CodeRate Parameter=Code Rate×1024, N>M, N≥K, and N, K, and M are allpositive integers.

In this embodiment of this application, the network device receives theindication information, and determines, based on the correspondencetable, the modulation scheme corresponding to the at least one CQIindex, where the correspondence table includes the N CQI indexes, the Mmodulation schemes, and the K code rate parameters, the at least one ofthe N CQI indexes corresponds to one type of modulation scheme, the K ofthe N CQI indexes are in a one-to-one correspondence with the K coderate parameters, and the product of the code rate corresponding to thefirst CQI index of the N CQI indexes and the modulation order of themodulation scheme corresponding to the first CQI index is a valuegreater than 0 and less than 0.0781, where Code Rate Parameter=CodeRate×1024, N>M, N≥K, and N, K, and M are all positive integers; and thenetwork device sends the indication information, so that the networkdevice determines, according to the indication information, themodulation scheme corresponding to the at least one CQI index. In otherwords, this application can be applied to a system that requiresspectrum efficiency lower than 0.0781, that is, an area in a bad channelcondition is covered, to ensure that a user can perform communication ona deep fading channel.

In a possible implementation, the K code rate parameters include a valuegreater than 0 and less than 40.

In a possible implementation, the N CQI indexes in the correspondencetable are arranged in ascending order, products of modulation orders ofmodulation schemes corresponding to all of the first P CQI indexes ofthe N CQI indexes and code rate parameters corresponding to all of thefirst P CQI indexes are arranged in ascending order, and a product of amodulation order of a modulation scheme corresponding to a (P+h)^(th)CQI index and a code rate parameter corresponding to the (P+h)^(th) CQIindex is less than a product of a modulation order of a modulationscheme corresponding to a P^(th) CQI index and a code rate parametercorresponding to the P^(th) CQI index, where N>P+h, h is a value rangingfrom 1 to N−X, and X>P.

A spectrum efficiency value less than 0.0781 that corresponds to a CQIindex may be arranged behind a maximum spectrum efficiency value, sothat a terminal device can determine, as required, a quantity of bitsincluded in channel quality indication information.

According to a seventeenth aspect, a communication method is provided,where the communication method includes: determining, by a networkdevice, indication information based on a correspondence table, wherethe indication information is used to indicate at least one modulationand coding scheme MCS index, the correspondence table includes N MCSindexes, M modulation schemes, and K code rate parameters, at least oneof the N MCS indexes corresponds to one type of modulation scheme, K ofthe N MCS indexes are in a one-to-one correspondence with the K coderate parameters, and a product of a code rate corresponding to a firstMCS index of the N MCS indexes and a modulation order of a modulationscheme corresponding to the first MCS index is a value greater than 0and less than 0.0781, where Code Rate Parameter=Code Rate×1024, N>M,N≥K, and N, K, and M are all positive integers; and sending, by thenetwork device, the indication information.

In this embodiment of this application, the network device determinesthe indication information based on the correspondence table, where theindication information is used to indicate the at least one channelquality indicator MCS index, the correspondence table includes the N MCSindexes, the M modulation schemes, and the K code rate parameters, theat least one of the N MCS indexes corresponds to one type of modulationscheme, the K of the N MCS indexes are in a one-to-one correspondencewith the K code rate parameters, and the product of the code ratecorresponding to the first MCS index of the N MCS indexes and themodulation order of the modulation scheme corresponding to the first MCSindex is a value greater than 0 and less than 0.0781, where Code RateParameter=Code Rate×1024, N>M, N≥K, and N, K, and M are all positiveintegers; and the network device sends the indication information, sothat a terminal device determines, according to the indicationinformation, the modulation scheme corresponding to the at least one MCSindex. In other words, this application can be applied to a system thatrequires spectrum efficiency lower than 0.0781, that is, an area in abad channel condition is covered, to ensure that a user can performcommunication on a deep fading channel.

In a possible implementation, the K code rates include a value greaterthan 0 and less than 40, N≥K, and K is a positive integer.

In a possible implementation, the N MCS indexes in the correspondencetable are arranged in ascending order, products of modulation orders ofmodulation schemes corresponding to all of the first P MCS indexes ofthe N MCS indexes and code rate parameters corresponding to all of thefirst P MCS indexes are arranged in ascending order, and a product of amodulation order of a modulation scheme corresponding to a (P+h)^(th)MCS index and a code rate parameter corresponding to the (P+h)^(th) MCSindex is less than a product of a modulation order of a modulationscheme corresponding to a P^(th) MCS index and a code rate parametercorresponding to the P^(th) MCS index, where N>P+h, h is a value rangingfrom 1 to N−X, and X>P.

According to an eighteenth aspect, a communication method is provided,where the communication method includes: receiving, by a terminaldevice, indication information, where the indication information is usedto indicate at least one modulation and coding scheme MCS index; anddetermining, by the terminal device based on a correspondence table, amodulation and coding scheme corresponding to the at least one MCSindex, where the correspondence table includes N MCS indexes, Mmodulation schemes, and K code rate parameters, at least one of the NMCS indexes corresponds to one type of modulation scheme, K of the N MCSindexes are in a one-to-one correspondence with the K code rateparameters, and a product of a code rate parameter corresponding to afirst CQI index of the N MCS indexes and a modulation order of amodulation scheme corresponding to the first MCS index is a valuegreater than 0 and less than 0.0781, where Code Rate Parameter=CodeRate×1024, N>M, N≥K, and N, K, and M are all positive integers.

In a possible implementation, the K code rate parameters include a valuegreater than 0 and less than 40.

In a possible implementation, the N MCS indexes in the correspondencetable are arranged in ascending order, products of modulation orders ofmodulation schemes corresponding to all of the first P MCS indexes ofthe N MCS indexes and code rate parameters corresponding to all of thefirst P MCS indexes are arranged in ascending order, and a product of amodulation order of a modulation scheme corresponding to a (P+h)^(th)MCS index and a code rate parameter corresponding to the (P+h)^(th) MCSindex is less than a product of a modulation order of a modulationscheme corresponding to a P^(th) MCS index and a code rate parametercorresponding to the P^(th) MCS index, where N>P+h, h is a value rangingfrom 1 to N−X, and X>P.

According to a nineteenth aspect, a network device is provided,including a processor, a memory, and a communications interface. Theprocessor is connected to the memory and the communications interface.The memory is configured to store an instruction, the processor isconfigured to execute the instruction, and the communications interfaceis configured to communicate with another network element under controlof the processor. When the processor executes the instruction stored inthe memory, the processor is enabled to perform the method in thethirteenth aspect or any possible implementation of the thirteenthaspect.

According to a twentieth aspect, a terminal device is provided,including a processor, a memory, and a communications interface. Theprocessor is connected to the memory and the communications interface.The memory is configured to store an instruction, the processor isconfigured to execute the instruction, and the communications interfaceis configured to communicate with another network element under controlof the processor. When the processor executes the instruction stored inthe memory, the processor is enabled to perform the method in thefourteenth aspect or any possible implementation of the fourteenthaspect.

According to a twenty-first aspect, a computer storage medium isprovided, where the computer storage medium stores program code, and theprogram code is used to indicate an instruction used to perform themethod in the thirteenth aspect or any possible implementation of thethirteenth aspect.

According to a twenty-second aspect, a computer storage medium isprovided, where the computer storage medium stores program code, and theprogram code is used to indicate an instruction used to perform themethod in the fourteenth aspect or any possible implementation of thefourteenth aspect.

According to a twenty-third aspect, a network device is provided, wherethe network device includes a module configured to perform the method inthe thirteenth aspect or any possible implementation of the thirteenthaspect.

According to a twenty-fourth aspect, a terminal device is provided,where the terminal device includes a module configured to perform themethod in the fourteenth aspect or any possible implementation of thefourteenth aspect.

According to a twenty-fifth aspect, a system is provided, where thesystem includes: the network device in the twenty-third aspect and theterminal device in the twenty-fourth aspect.

According to a twenty-sixth aspect, a terminal device is provided,including a processor, a memory, and a communications interface. Theprocessor is connected to the memory and the communications interface.The memory is configured to store an instruction, the processor isconfigured to execute the instruction, and the communications interfaceis configured to communicate with another network element under controlof the processor. When the processor executes the instruction stored inthe memory, the processor is enabled to perform the method in thefifteenth aspect or any possible implementation of the fifteenth aspect.

According to a twenty-seventh aspect, a network device is provided,including a processor, a memory, and a communications interface. Theprocessor is connected to the memory and the communications interface.The memory is configured to store an instruction, the processor isconfigured to execute the instruction, and the communications interfaceis configured to communicate with another network element under controlof the processor. When the processor executes the instruction stored inthe memory, the processor is enabled to perform the method in thesixteenth aspect or any possible implementation of the sixteenth aspect.

According to a twenty-eighth aspect, a computer storage medium isprovided, where the computer storage medium stores program code, and theprogram code is used to indicate an instruction used to perform themethod in the fifteenth aspect or any possible implementation of thefifteenth aspect.

According to a twenty-ninth aspect, a computer storage medium isprovided, where the computer storage medium stores program code, and theprogram code is used to indicate an instruction used to perform themethod in the sixteenth aspect or any possible implementation of thesixteenth aspect.

According to a thirtieth aspect, a terminal device is provided, wherethe terminal device includes a module configured to perform the methodin the fifteenth aspect or any possible implementation of the fifteenthaspect.

According to a thirty-first aspect, a network device is provided, wherethe network device includes a module configured to perform the method inthe sixteenth aspect or any possible implementation of the sixteenthaspect.

According to a thirty-second aspect, a system is provided, where thesystem includes: the terminal device in the thirtieth aspect and thenetwork device in the thirty-first aspect.

According to a thirty-third aspect, a network device is provided,including a processor, a memory, and a communications interface. Theprocessor is connected to the memory and the communications interface.The memory is configured to store an instruction, the processor isconfigured to execute the instruction, and the communications interfaceis configured to communicate with another network element under controlof the processor. When the processor executes the instruction stored inthe memory, the processor is enabled to perform the method in theseventeenth aspect or any possible implementation of the seventeenthaspect.

According to a thirty-fourth aspect, a terminal device is provided,including a processor, a memory, and a communications interface. Theprocessor is connected to the memory and the communications interface.The memory is configured to store an instruction, the processor isconfigured to execute the instruction, and the communications interfaceis configured to communicate with another network element under controlof the processor. When the processor executes the instruction stored inthe memory, the processor is enabled to perform the method in theeighteenth aspect or any possible implementation of the eighteenthaspect.

According to a thirty-fifth aspect, a computer storage medium isprovided, where the computer storage medium stores program code, and theprogram code is used to indicate an instruction used to perform themethod in the seventeenth aspect or any possible implementation of theseventeenth aspect.

According to a thirty-sixth aspect, a computer storage medium isprovided, where the computer storage medium stores program code, and theprogram code is used to indicate an instruction used to perform themethod in the eighteenth aspect or any possible implementation of theeighteenth aspect.

According to a thirty-seventh aspect, a network device is provided,where the network device includes a module configured to perform themethod in the seventeenth aspect or any possible implementation of theseventeenth aspect.

According to a thirty-eighth aspect, a terminal device is provided,where the terminal device includes a module configured to perform themethod in the eighteenth aspect or any possible implementation of theeighteenth aspect.

According to a thirty-ninth aspect, a system is provided, where thesystem includes: the network device in the thirty-seventh aspect and theterminal device in the thirty-eighth aspect.

According to the foregoing solutions, in the embodiments of thisapplication, the network device may receive a channel quality parameterthat corresponds to a BLER in the first BLER subset in the first BLERset and that is sent by the terminal device, and determine, based onchannel quality parameters corresponding to some BLERs in the first BLERsubset and the channel quality parameter difference between the channelquality parameter corresponding to each BLER in the second BLER subsetand the channel quality parameter corresponding to the at least one BLERin the first BLER subset, channel quality parameters corresponding toall BLERs in the second BLER subset. In other words, the network devicecan determine channel quality parameters corresponding to all BLERs inthe first BLER set, and therefore the terminal device does not need tosend the channel quality parameters corresponding to all the BLERs inthe first BLER set, thereby reducing signaling overheads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an application scenario according to anembodiment of this application;

FIG. 2 is a value table of a CQI absolute indicator value in the currentsystem;

FIG. 3 is a value table of a CQI differential indicator value in thecurrent system;

FIG. 4 is an interaction flowchart of a channel quality feedback methodaccording to an embodiment of this application;

FIG. 5 is a schematic diagram of an SINR fluctuation according to anembodiment of this application;

FIG. 6 is a simulation diagram of a time correlation according to anembodiment of this application;

FIG. 7 is a schematic diagram of a reference time according to anembodiment of this application;

FIG. 8 is another schematic diagram of a reference time according to anembodiment of this application;

FIG. 9 is a schematic diagram of a CQI table according to an embodimentof this application;

FIG. 10 is an interaction diagram of a modulation and coding policyindication method according to an embodiment of this application;

FIG. 11A and FIG. 11B are a schematic diagram of an MCS table accordingto an embodiment of this application;

FIG. 12 is a schematic diagram of a logical structure of a networkdevice according to an embodiment of this application;

FIG. 13 is a schematic diagram of a physical structure of a networkdevice according to an embodiment of this application;

FIG. 14 is a schematic diagram of a logical structure of a terminaldevice according to an embodiment of this application;

FIG. 15 is a schematic diagram of a physical structure of a terminaldevice according to an embodiment of this application;

FIG. 16 is a schematic diagram of a logical structure of a networkdevice according to an embodiment of this application;

FIG. 17 is a schematic diagram of a physical structure of a networkdevice according to an embodiment of this application;

FIG. 18 is a schematic diagram of a logical structure of a terminaldevice according to an embodiment of this application;

FIG. 19 is a schematic diagram of a physical structure of a terminaldevice according to an embodiment of this application;

FIG. 20 is a schematic flowchart of a communication method according toan embodiment of this application;

FIG. 21 is a schematic flowchart of channel quality parameterdifferences of different terminal devices;

FIG. 22 is a schematic flowchart of a communication method according toan embodiment of this application;

FIG. 23 is a schematic flowchart of a communication method according toan embodiment of this application;

FIG. 24 is a schematic block diagram of a network device according to anembodiment of this application;

FIG. 25 is a schematic structural diagram of a network device accordingto an embodiment of this application;

FIG. 26 is a schematic block diagram of a terminal device according toan embodiment of this application;

FIG. 27 is a schematic structural diagram of a terminal device accordingto an embodiment of this application;

FIG. 28 is a schematic block diagram of a system according to anembodiment of this application;

FIG. 29 is a schematic structural diagram of a terminal device accordingto an embodiment of this application;

FIG. 30 is a schematic structural diagram of a terminal device accordingto an embodiment of this application;

FIG. 31 is a schematic block diagram of a network device according to anembodiment of this application;

FIG. 32 is a schematic structural diagram of a network device accordingto an embodiment of this application; and

FIG. 33 is a schematic block diagram of a system according to anembodiment of this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following describes technical solutions in this application withreference to the accompanying drawings.

The following describes the embodiments of this application withreference to the accompanying drawings in the embodiments of thisapplication.

A preset set in the embodiments of this application may be a set presetin a network device and a terminal device.

The embodiments of this application may be applied to a wirelesscommunications system. The wireless communications system usuallyincludes a cell, and each cell includes one base station (BS). As shownin FIG. 1, a base station provides a communication service for aplurality of terminal devices, and the base station is connected to acore network device. The base station includes a baseband unit (BBU) anda remote radio unit (RRU). The BBU and the RRU may be placed indifferent places. For example, the RRU is remotely deployed and isplaced in an open area far away from a heavy-traffic area, and the BBUis placed in a central equipment room. Alternatively, the BBU and theRRU may be placed in a same equipment room. The BBU and the RRU may bedifferent components in a same rack.

It should be noted that the wireless communications system in theembodiments of this application includes but is not limited to anarrowband internet of things (NB-IoT) system, a global system formobile communications (GSM), an enhanced data rates for GSM evolution(EDGE) system, a wideband code division multiple access (WCDMA) system,a code division multiple access 2000 (CDMA2000) system, a timedivision-synchronous code division multiple access (TD-SCDMA) system, along term evolution (LTE) system, a 5G system, and a future mobilecommunications system.

The base station in the embodiments of this application is an apparatusthat is deployed in a radio access network and that is configured toprovide a wireless communication function for the terminal device. Thebase station may include a macro base station, a micro base station(also referred to as a small cell), a relay station, an access point, atransmission reception point (TRP), and the like in various forms. Insystems that use different radio access technologies, names of a devicethat has a base station function may be different. For example, in anLTE system, the device is referred to as an evolved NodeB (eNB oreNodeB), and in a 3^(rd) generation (3G) system, the device is referredto as a NodeB (NB). For ease of description, in all the embodiments ofthis application, all the foregoing apparatuses that provide a wirelesscommunication function for the terminal device are collectively referredto as the network device.

The terminal device in the embodiments of this application may includevarious handheld devices, vehicle-mounted devices, wearable devices, orcomputing devices that have a wireless communication function, or otherprocessing devices connected to a wireless modem. The terminal devicemay also be referred to as a mobile station (MS), a terminal, or mayinclude a subscriber unit, a cellular phone, a smartphone, a wirelessdata card, a personal digital assistant (PDA) computer, a tabletcomputer, a wireless modem, a handset, a laptop computer, a machine typecommunication (MTC) terminal, and the like. For ease of description, thedevices described above are collectively referred to as the terminaldevice in all the embodiments of this application.

For example, a 5G communications system supports a plurality of servicetypes, different deployment scenarios, and a wider spectrum range. Theplurality of service types include but are not limited to enhancedmobile broadband (eMBB), massive machine type communication (mMTC),ultra-reliable and low latency communications (URLLC), a multimediabroadcast multicast service (MBMS), a positioning service, and the like.The different deployment scenarios include but are not limited to anindoor hotspot scenario, a dense urban scenario, a rural scenario, anurban macro scenario, a high-speed railway scenario, and the like. Thewider spectrum range indicates that 5G supports a spectrum range up to100 GHz, and the spectrum range includes a low-frequency part less than6 GHz and a high-frequency part ranging from 6 GHz to 100 GHz.

Compared with a 4G communications system, one feature of the 5Gcommunications system is that a URLLC service is supported. There are aplurality of URLLC service types, and typical examples includeindustrial control, industrial production process automation, humancomputer interaction, telemedicine, and the like. To better quantizeperformance indicators of a URLLC service to provide a reference inputand evaluation criterion for designing the 5G system, the 3GPP RAN andRAN1 working groups define the following performance indicators of theURLLC service.

A latency is a transmission time that is required when a service dataunit (SDU) of a user application layer packet is transmitted from aradio protocol stack layer 2/3 of a transmit end to a radio protocolstack layer 2/3 of a receive end. Both an uplink user plane latencyrequirement and a downlink user plane latency requirement of a URLLCservice are 0.5 ms, and the foregoing requirements are applicable onlywhen neither a base station nor a terminal is in a discontinuousreception state. It should be noted that the latency performancerequirement of 0.5 ms herein means an average latency of a data packet.

Reliability is a success probability that X bits are correctlytransmitted from the transmit end to the receive end in a particulartime (e.g., L seconds) in a given channel quality condition. Theforegoing time is also defined as a time that is required when a servicedata unit (SDU) of a user application layer packet is transmitted from aradio protocol stack layer 2/3 of a transmit end to a radio protocolstack layer 2/3 of a receive end. For a URLLC service, a typicalrequirement is achieving reliability of 99.999% in 1 ms. It should benoted that the foregoing performance indicator is merely a typicalvalue. Specifically, the URLLC service may have different reliabilityrequirements. For example, some extremely hash industrial controlrequires an end-to-end latency of 0.25 ms and a transmission successprobability of 99.9999999%.

A system capacity is a maximum cell throughput of a system when aparticular proportion of user interruption is met. The user interruptionherein means that the system cannot meet a reliability requirement ofthe URLLC service in a particular latency range.

It may be learned from the foregoing description that a strictreliability requirement needs to be met in a harsh transmission latencycondition, and each transmission, especially retransmission, needs to beas correct as possible. However, robust reduction of a modulation andcoding level only leads to low system transmission efficiency.Therefore, a channel quality feedback needs to be enhanced, so that notonly transmission reliability can be ensured, but also scheduling withexcessively low transmission efficiency can be avoided.

For example, a CQI feedback technology is a typical channel qualityfeedback technology. In a long term evolution (LTE) system, the CQIfeedback technology includes an absolute indicator value feedback and adifferential indicator value feedback. A CQI absolute indicator value isshown in a table in FIG. 2. As shown in the figure, each CQI indexcorresponds to modulation and a code rate in a specified channelcondition. CQI absolute indicator values in a table form a channelquality indicator CQI set.

In the CQI absolute indicator value feedback, after obtaining currentchannel quality through measurement, the terminal device feeds back onetype of feedback information, and the feedback information correspondsto a CQI index corresponding to the current channel quality. In otherwords, one type of feedback information corresponds to one type of CQIindex. For example, if 16 types of CQI indexes are included, four-bitfeedback information needs to be used for a feedback. Usually, a fewtypes of CQI indexes are set to reduce feedback overheads. For example,only 16 types of CQI indexes are set. This indication is relativelycoarse, and precision is not high.

Further, relatively large overheads are caused when an absoluteindicator value feedback is used. In the industry, a CQI is graduallyfed back by using a differential indicator value feedback. In thedifferential indicator value feedback, a CQI reference index value isfirst determined, and an offset is calculated for each remaining CQIindex by using the reference index value as a reference. Therefore, theterminal device only needs to feed back feedback informationcorresponding to the offset. To reduce overheads of feedbackinformation, several optional offsets are determined to form a channelquality indicator CQI set, and one type of feedback informationcorresponds to one offset. For example, a channel quality indicator CQIset is {−1, 0, 1, 2}. The terminal device may feed back the four offsetsby using two-bit feedback information. Currently, the channel qualityindicator CQI set, for example, a channel quality indicator CQI setshown in a table in FIG. 3, is specified for all cases in the industry.Reference index values are different in different feedback scenarios,and definitions of offsets are also different. For example, an offsetbetween a wideband CQI index of a code word 0 and a wideband CQI indexof a code word 1 is calculated by using the wideband CQI index of thecode word 1 as a reference index value. For example, an offset between asubband CQI index and a wideband CQI index is calculated by using thewideband CQI index as a reference index value. For example, an offsetbetween a CQI index of each of selected M subbands with best signalquality and a wideband CQI index is calculated by using the wideband CQIindex as a reference index value.

In a specific feedback scenario, all terminal devices use a same channelquality indicator set, resulting in an inaccurate channel qualityindication. For example, for the channel quality indicator set in FIG.3, when an offset is 2, feedback information fed back by the terminaldevice is 0, and when an offset is 5, the feedback information fed backby the terminal device is still 10. Therefore, the terminal devicecannot accurately indicate current channel quality of a channel.

Regardless of the absolute indicator value feedback or the differentialindicator value feedback, feedbacks are not accurate because allterminal devices use the same set to provide feedbacks. To resolve theforegoing problem, in the embodiments of this application, a channelquality indicator set is independently configured for each terminaldevice. It should be noted that a channel quality indicator valueincluded in the channel quality indicator set may be an absoluteindicator value or a differential indicator value.

It should be noted that a quantity of channel quality indicator valuesincluded in the channel quality indicator set configured for theterminal device is not limited in the embodiments of this application,and there may be one or more channel quality indicator values. Thechannel quality indicator value is used to indicate channel quality.

For example, the channel quality indicator set includes a channelquality absolute indicator value (for example, a CQI index). The networkdevice configures one channel quality indicator set for each terminaldevice. The channel quality indicator set may be a preset set or asubset of the preset set specified in a protocol, the preset setspecified in the protocol includes a relatively large quantity ofabsolute indicator values, a division granularity is relatively fine,and each absolute indicator value corresponds to one modulation andcoding policy in a specific channel condition. If a channel qualitychange of each terminal device varies, a configured channel qualityindicator set also varies, that is, a subset selected from the presetset varies. Alternatively, the channel quality indicator set configuredby the network device for each terminal device may be at least one of aplurality of preset sets specified in a protocol. For example, thenetwork device configures a plurality of channel quality indicator setsfor one terminal device, and one channel quality indicator setcorresponds to one service type. When feeding back different servicetypes, the terminal device provides feedbacks by using different channelquality indicator sets. Optionally, at least two of the plurality ofpreset sets include different quantities of absolute indicator values.

For another example, the channel quality indicator set includes adifferential indicator value (for example, an offset of a CQI index).The network device configures one channel quality indicator set for eachterminal device, where the channel quality indicator set adapts to achannel quality change of the terminal device. For example, if theterminal device is a center user, it indicates that channel quality ofthe terminal device is relatively good, an SINR fluctuation isrelatively small, and a fluctuation in a differential indicator value inthe channel quality indicator set is relatively small. If the terminaldevice is an edge user, it indicates that channel quality of theterminal device is relatively poor, an SINR fluctuation is relativelylarge, and a fluctuation in a differential indicator value in thechannel quality indicator set is relatively large. Each terminal devicecan accurately indicate channel quality of the terminal device by usingfeedback information.

The channel quality indicator set specially configured for the terminaldevice is used, so that the terminal device can accurately feed backcurrent channel quality.

A channel quality feedback method provided in the embodiments of thisapplication is described below in detail.

FIG. 4 is a schematic flowchart of a channel quality feedback methodaccording to an embodiment of this application. The method is describedfrom a perspective of interaction between a network device and aterminal device, and the method may include but is not limited to thefollowing steps:

Step S10: The network device determines a channel quality indicator setof the terminal device, where the channel quality indicator set includesa channel quality indicator value, and the channel quality indicatorvalue is used to indicate channel quality.

Step S11: The network device sends the channel quality indicator set tothe terminal device.

Step S12: The terminal device obtains the channel quality indicator setdetermined by the network device for the terminal device, where thechannel quality indicator set includes a channel quality indicatorvalue, and the channel quality indicator value is used to indicatechannel quality.

Step S13: The terminal device sends feedback information to the networkdevice, where the feedback information is used to indicate a targetchannel quality indicator value, the target channel quality indicatorvalue is a channel quality indicator value in the channel qualityindicator set, and the target channel quality indicator value is used todetermine current channel quality of a channel.

Step S14: The network device receives the feedback information todetermine channel quality.

In this embodiment of this application, the network device independentlydetermines the channel quality indicator set for the terminal device,and sends the determined channel quality indicator set to the terminaldevice. The terminal device subsequently feeds back the channel qualityto the network device based on the channel quality indicator set.Optionally, that the network device independently determines the channelquality indicator set for the terminal device may be that the networkdevice configures the channel quality indicator set for the terminaldevice.

Optionally, the channel quality indicator set includes at least onechannel quality indicator value, and the channel quality indicator valueis used to indicate channel quality. The channel quality indicator valuemay be a channel quality differential indicator value or a channelquality absolute indicator value, the channel quality differentialindicator value is used to indicate an offset between a channel qualitymeasurement value and a channel quality reference value, and the channelquality absolute indicator value is used to indicate a channel qualitymeasurement value. Optionally, the channel quality may be a CQI, an MCSor a BLER, and this is not limited in this application. The CQI, theMCS, and the BLER are merely used as examples for description herein.

Optionally, if the channel quality is a CQI, the channel qualitymeasurement value may be a CQI index in a current channel qualitycondition, and the channel quality reference value may be a CQI indexthat is fed back at a time closest to a reference time corresponding tothe measurement value (which may be a CQI index that is periodically fedback at the time closest to the reference time corresponding to themeasurement value, or may be a CQI index that is aperiodically fed backat the time closest to the reference time corresponding to themeasurement value, or may be a channel quality value that is fed back atthe time closest to the reference time corresponding to the measurementvalue and that is in a specific channel quality reporting set).

The reference time corresponding to the measurement value may be areference measurement time corresponding to the measurement value or ameasurement reporting time corresponding to the measurement value. Themeasurement reporting time corresponding to the measurement value is atime for sending feedback information (the feedback information is usedto indicate channel quality to the network device based on the channelquality measurement value) for the channel quality measurement value bythe terminal device, and the reference measurement time is usuallydefined as a preset time period before the measurement reporting time(for example, two subframes before the measurement reporting time). Theterminal device measures the channel quality to obtain the channelquality measurement value, and a measurement time for measuring thechannel quality by the terminal device overlaps with the referencemeasurement time, or there are a plurality of measurement times, and thereference measurement time is one of the measurement times. As shown inFIG. 7, t3 represents a measurement reporting time, t2 represents areference measurement time, and t1 represents a measurement time. InFIG. 7, an interval between t2 and t3 is one subframe, and t1 and t2overlap. As shown in FIG. 8, t3 represents a measurement reporting time,t2 represents a reference measurement time, and t1 represents ameasurement time. In FIG. 8, an interval between t2 and t3 is onesubframe, t1 spans three subframes (that is, the terminal devicemeasures channel quality in all the three subframes, and finally feedsback a channel quality average), and t2 is a subframe in t1. Theinterval between t2 and t3 is usually specified in a protocol.

Optionally, if the channel quality is an MCS, the channel qualitymeasurement value may be an MCS level to match a target block error ratewith a current channel quality condition, and the channel qualityreference value may be an MCS level used for current transmission.

Optionally, if the channel quality is a BLER, the channel qualitymeasurement value may be a BLER level corresponding to an MCS used forcurrent transmission in a current channel quality condition, and thechannel quality reference value may be an expected target BLER level incurrent transmission. BLER levels may include {1, 2, 3, 4, 5}, and BLERscorresponding to the BLER levels are {10{circumflex over ( )}−1,10{circumflex over ( )}−2, 10{circumflex over ( )}−3, 10{circumflex over( )}−4, 10{circumflex over ( )}−5}.

In an optional implementation, a channel quality indicator value in thechannel quality indicator set is a channel quality differentialindicator value, that is, the channel quality indicator value is anoffset between a channel quality measurement value and a channel qualityreference value. Because channel quality changes of different terminaldevices are different, a channel quality indicator set needs to beindependently configured for each terminal device. A channel qualityindicator value in the channel quality indicator set is set based on achannel quality change of the terminal device, and can accuratelyreflect the channel quality change of the terminal device.

For example, a received signal to interference plus noise ratio (Signalto Interference plus Noise Ratio, SINR) of a terminal device on a celledge or in a cell center varies with time. As shown in FIG. 5, a solidline is a cumulative distribution function (cumulative distributionfunction, CDF) distribution curve of an SINR fluctuation of a cellcenter user at intervals of 10 ms, and SINR fluctuations correspondingto 50%, 80%, and 95% are respectively 0.8 dB, 1.2 dB, and 1.7 dB. Adotted line in FIG. 5 is a CDF distribution curve of an SINR fluctuationof a cell edge user at intervals of 10 ms, and SINR fluctuationscorresponding to 50%, 80%, and 95% are respectively 0.9 dB, 2 dB, and4.3 dB, as shown in the following table:

50% 80% 95% Center user 0.8 dB 1.2 dB 1.7 dB Edge user 0.9 dB   2 dB 4.3dB

It may be learned from the foregoing table that an SINR fluctuation ofthe cell edge user is significantly higher than that of the center user.The network device may separately configure channel quality indicatorsets for the edge user and the center user. The following uses anexample in which the channel quality is a CQI for description. Thechannel quality measurement value is a CQI index obtained throughmeasurement, and the channel quality reference value is a CQI referenceindex value. The differential indicator value is an offset between theCQI index obtained through measurement and the CQI reference indexvalue.

For example, a channel quality indicator set configured for the centeruser is {−1.2, −0.8, 0, 0.8}, and a channel quality indicator setconfigured for the edge user is {−3, −1.3, 0, 1.3}. A fluctuationbetween channel quality indicator values in the channel qualityindicator set configured for the center user is relatively small, and afluctuation between channel quality indicator values in the channelquality indicator set configured for the edge user is relatively large.This is mainly to adapt to characteristics of channel quality changes ofthe center user and the edge user.

It may be learned from the foregoing description that, although thereare only four differential indicator values in the channel qualityindicator set and corresponding UCI signaling has two bits, each usercan accurately indicate a current channel quality fluctuation by using auser-specific channel quality indicator set.

In the current system, there is only one channel quality indicator setof {−2, −1, 0, 1} in a scenario. For example, the first value indicatesan excessive downward offset for the center user (a relatively low MCSlevel is used for subsequent transmission), resulting in a waste oftransmission resources. The first value indicates an insufficientdownward offset for the edge user, and therefore a base stationconfigures a relatively high MCS level for the terminal, resulting in atransmission error.

In addition to determining a differential indicator value in the channelquality indicator set based on a cell attribute of the center user orthe edge user of the terminal device, configuration may be performedbased on a channel quality historical value reported by the terminaldevice. For example, if CQI indexes historically reported by theterminal device are relatively small or fluctuate greatly, a relativelylarge channel quality indicator value is set in the channel qualityindicator set. Otherwise, a relatively small value is set.

Optionally, a differential indicator value in the channel qualityindicator set may be an integer and/or a fraction. For example, thechannel quality indicator set is {−0.3, 0, 0.3, 0.6}.

Optionally, differential indicator values in the channel qualityindicator set may be nonuniformly distributed. For example, the channelquality indicator set is {−5, −1, 0, 1, 5}.

Further, optionally, a channel quality change is also correlated toduration of a time period. FIG. 6 is a simulation diagram of duration ofa time period and an SINR correlation of a channel according to anembodiment of this application. Horizontal coordinates in the simulationdiagram represent a time period in milliseconds, and verticalcoordinates represent an SINR correlation coefficient. As shown in thefigure, a longer time period indicates a smaller SINR correlation of thechannel and a larger fluctuation in a channel quality differentialindicator value in a corresponding channel quality indicator set. Incontrast, a shorter time period indicates a larger SINR correlation ofthe channel and a smaller fluctuation in a channel quality differentialindicator value in a corresponding channel quality indicator set.

In this embodiment of this application, the channel quality differentialindicator value in the channel quality indicator set is used to indicatethe offset between the channel quality measurement value and the channelquality reference value, that is, a time period between the referencetime corresponding to the channel quality measurement value and areference time corresponding to the channel quality reference valuedetermines a fluctuation in the differential indicator value in thechannel quality indicator set. It should be noted that the referencetime corresponding to the channel quality reference value is a referencemeasurement time corresponding to the channel quality reference value ora measurement reporting time corresponding to the channel qualityreference value. A definition of the reference measurement timecorresponding to the channel quality reference value herein is the sameas that of the reference measurement time corresponding to themeasurement value, and a definition of the measurement reporting timecorresponding to the channel quality reference value herein is the sameas that of the measurement reporting time corresponding to themeasurement value. Details are not described herein again.

In this embodiment of this application, for a same terminal device, itis set that intervals of a plurality of time periods respectivelycorrespond to a plurality of channel quality indicator sets, and theintervals of the plurality of time periods do not overlap. A time periodis a time difference between a reference time corresponding to ameasurement value and a reference time corresponding to a channelquality reference value. An interval of a first time period and aninterval of a second time period in this embodiment of this applicationmay be intervals of any two time periods of the intervals of theplurality of time periods. The interval of the first time periodcorresponds to a first channel quality indicator set, and the intervalof the second time period corresponds to a second channel qualityindicator set.

Optionally, if a time period in the interval of the first time period isless than a time period in the interval of the second time period, afluctuation in a differential indicator value in the first channelquality indicator set is less than a fluctuation in a differentialindicator value in the second channel quality indicator set. Forexample, a variance of the differential indicator values in the firstchannel quality indicator set may be less than a variance of thedifferential indicator values in the second channel quality indicatorset.

For example, when the network device sets an interval of a time periodto be less than 5 ms, a corresponding channel quality indicator set is{−0.5, 0, 0.5, 1}; when the network device sets an interval of a timeperiod to be greater than 5 ms and less than 10 ms, a correspondingchannel quality indicator set is {−1, 0, 1, 2}; when the network devicesets an interval of a time period to be greater than 10 ms, acorresponding channel quality indicator set is {−2, 0, 2, 4}.

Further, optionally, a channel quality change is also correlated to avalue of a reference BLER. For example, if a BLER corresponding to ameasurement value is the same as a BLER corresponding to a referencevalue, an SINR difference is relatively small, and correspondingly, afluctuation in a channel quality differential indicator value in achannel quality indicator set is relatively small. If a BLERcorresponding to a measurement value is different from a BLERcorresponding to a reference value, an SINR difference is relativelylarge, and correspondingly, a fluctuation in a channel qualitydifferential indicator value in a channel quality indicator set isrelatively large. In addition, if the BLER corresponding to themeasurement value is greater than the BLER corresponding to thereference value, the differential indicator value in the channel qualityindicator set is greater than 0 or equal to 0. If the BLER correspondingto the measurement value is less than the BLER corresponding to thereference value, the differential indicator value in the channel qualityindicator set is less than 0 or equal to 0.

In this embodiment of this application, for a same terminal device, itis set that intervals of a plurality of BLER differences respectivelycorrespond to a plurality of channel quality indicator sets, and theintervals of the plurality of BLER differences do not overlap. A BLERdifference is a block error rate difference between a BLER correspondingto a measurement value and a BLER corresponding to a channel qualityreference value. An interval of a first BLER difference and an intervalof a second BLER difference in this embodiment of this application maybe intervals of any two BLER differences of the intervals of theplurality of BLER differences. The interval of the first BLER differencecorresponds to a first channel quality indicator set, and the intervalof the second BLER difference corresponds to a second channel qualityindicator set.

Optionally, if an absolute indicator value of a BLER difference in theinterval of the first BLER difference is less than an absolute indicatorvalue of a BLER difference in the interval of the second BLERdifference, a fluctuation in a differential indicator value in the firstchannel quality indicator set is less than a fluctuation in adifferential indicator value in the second channel quality indicatorset. For example, a variance of the differential indicator values in thefirst channel quality indicator set may be less than a variance of thedifferential indicator values in the second channel quality indicatorset.

Optionally, different channel quality indicator sets may be furtherdetermined based on a result of comparing a BLER difference in a BLERdifference interval with 0. If a BLER difference is 0, a channel qualityindicator set is {−0.5, 0, 0.5, 1}. If a BLER difference is greater than0, a channel quality indicator set is {0, 1, 2, 3}. If a BLER differenceis less than 0, a channel quality indicator set is {−3, −2, −1, 0}.

The network device sends the configured channel quality indicator set tothe terminal device. Optionally, the channel quality indicator set maybe sent by using a higher layer signaling configuration, or the channelquality indicator set may be sent by using a MAC CE signalingconfiguration. Further, the channel quality indicator set may bealternatively sent by using a user-specific signaling configuration.

The terminal device obtains the channel quality indicator set determinedby the network device for the terminal device, where the channel qualityindicator set includes a channel quality differential indicator value.For example, the channel quality indicator set determined by the networkdevice for the terminal device is {−1, 0, 1, 2}. The terminal devicemeasures a channel and feeds back channel quality. For example, theterminal device measures a channel at a moment t1, obtains a channelquality measurement value CQI of 3, and uses a CQI index fed back at amoment to as a reference value. It is assumed that the CQI index fedback at the moment to is 2, and the moment to is before the moment t1. Adifference between the channel quality measurement value and the channelquality reference value is 3−2=1.

The following table shows a correspondence between feedback informationand a CQI differential indicator value. It may be learned from thefollowing table that the terminal device sends feedback information of10.

UCI bit CQI differential indicator value 00 −1 01 0 10 1 11 2

After receiving the feedback information, the network device may obtainthe channel quality measurement value through calculation based on thechannel quality reference value. The channel quality measurement valueis used to indicate current channel quality, and further affects an MCSand/or power configured during subsequent scheduling by the networkdevice.

Optionally, for a same terminal device, channel quality indicator setsconfigured by the network device are a plurality of channel qualityindicator sets that respectively correspond to intervals of a pluralityof time periods. For example, when the network device sets an intervalof a time period to be less than 5 ms, a corresponding channel qualityindicator set is {−0.5, 0, 0.5, 1}, when the network device sets aninterval of a time period to be greater than 5 ms and less than 10 ms, acorresponding channel quality indicator set is {−1, 0, 1, 2}, and whenthe network device sets an interval of a time period to be greater than10 ms, a corresponding channel quality indicator set is {−2, 0, 2, 4}.

The terminal device measures a channel at a moment t1, obtains a channelquality measurement value CQI of 3, and uses a CQI index fed back at amoment to as a reference value. It is assumed that the CQI index fedback at the moment to is 2, and the moment to is before the moment t1. Adifference between the channel quality measurement value and the channelquality reference value is 3−2=1. If a time period between the moment t1and the moment to is 6 ms, a corresponding channel quality indicator setis {−1, 0, 1, 2}, and feedback information corresponding to thedifferential indicator value of 1 is 10. The terminal device sends thefeedback information of 10.

After receiving the feedback information of 10, the network device firstneeds to determine a first target channel quality indicator setcorresponding to the feedback information. Specifically, optionally, thenetwork device determines a time period between a reference timecorresponding to the measurement value and a reference timecorresponding to the reference value, determines that the time periodbelongs to an interval of a target time period of preset intervals of aplurality of time periods, and uses a channel quality indicator setcorresponding to the interval of the target time period as the firsttarget channel quality indicator set. For example, the network devicedetermines that the first target channel quality indicator set is achannel quality indicator set of {−1, 0, 1, 2} corresponding to aninterval of a time period greater than 5 ms and less than 10 ms.Further, a target differential indicator value is determined as 1 basedon the feedback information of 10, and then the channel qualitymeasurement value is obtained based on the channel quality referencevalue, where the channel quality measurement value is used to indicatecurrent channel quality, and further affects an MCS and/or powerconfigured during subsequent scheduling by the network device.

Optionally, for a same terminal device, channel quality indicator setsconfigured by the network device are a plurality of channel qualityindicator sets that respectively correspond to intervals of a pluralityof BLER differences, and the intervals of the plurality of BLERdifferences do not overlap. An interval of a third block error ratedifference and an interval of a fourth block error rate difference inthis embodiment of this application may be intervals of any two blockerror rate differences of the intervals of the plurality of BLERdifferences. The interval of the third block error rate differencecorresponds to a third channel quality indicator set, and the intervalof the fourth block error rate difference corresponds to a fourthchannel quality indicator set.

For example, the plurality of channel quality indicator sets thatrespectively correspond to the intervals that are of the plurality ofBLER differences and that are set by the network device are as follows:If a BLER difference is 0, a channel quality indicator set is {−0.5, 0,0.5, 1}. If a BLER difference is greater than 0, a channel qualityindicator set is {0, 1, 2, 3}. If a BLER difference is less than 0, achannel quality indicator set is {−3, −2, −1, 0}.

The terminal device measures a channel at a moment t1, obtains a channelquality measurement value CQI of 2 and a reference BLER of 1%, and usesa CQI index fed back at a moment to as a reference value. It is assumedthat the CQI index fed back at the moment to is 2, a reference BLER of10%, and the moment to is before the moment t1. A difference between thechannel quality measurement value and the channel quality referencevalue is 2-2=0. If a BLER difference between a BLER corresponding to themeasurement value and a BLER corresponding to the reference value isless than 0, a corresponding channel quality indicator set is {−3, −2,−1, 0}, and feedback information corresponding to the differentialindicator value 0 is 11. The terminal device sends the feedbackinformation of 11.

After receiving the feedback information of 11, the network device firstneeds to determine a second target channel quality indicator setcorresponding to the feedback information. Specifically, optionally, thenetwork device determines the BLER difference between the BLERcorresponding to the measurement value and the BLER corresponding to thereference value, determines that the BLER difference belongs to aninterval of a target BLER difference of preset intervals of a pluralityof BLER differences, and uses a channel quality indicator setcorresponding to the interval of the target BLER difference as thesecond target channel quality indicator set. For example, the networkdevice determines that the second target channel quality indicator setis a channel quality indicator set of {−3, −2, −1, 0} corresponding to aBLER difference interval less than 0. Further, a target differentialindicator value is determined as 0 based on the feedback information of11, and then the channel quality measurement value is obtained based onthe channel quality reference value, where the channel qualitymeasurement value is used to indicate current channel quality, andfurther affects an MCS and/or power configured during subsequentscheduling by the network device.

In an optional implementation, a channel quality indicator value in thechannel quality indicator set is a channel quality absolute indicatorvalue, and the channel quality absolute indicator value is used toindicate a channel quality measurement value, for example, a CQI indexobtained through measurement. Different users usually work in differentSINR intervals. For example, an edge user usually works in a relativelylow SINR, for example, −12 dB to −2 dB; a center user works in arelatively high SINR, for example, 15 dB to 25 dB. Therefore, ranges ofCQI indexes measured and fed back by different users are also different.To reduce feedback overheads and classify CQI types at a finergranularity, the network device independently configures a channelquality indicator set for each terminal device. An absolute indicatorvalue in the channel quality indicator set is set based on channelquality of the terminal device, and can accurately reflect a channelquality change of the terminal device.

Optionally, the channel quality indicator set configured by the networkdevice for the terminal device may be a preset set or a subset of thepreset set, and the preset set is a set specified in a protocol. FIG. 9may show the preset set specified in the protocol, and the preset setincludes 32 absolute indicator values. To reduce overheads, the networkdevice configures the preset set or a subset of the preset set for eachterminal device based on channel quality of the terminal device. Forexample, a channel quality indicator set configured by the networkdevice for an edge user is a set whose working interval is 0 to 15, anda channel quality indicator set configured by the network device for acenter user is a set whose working interval is 16 to 31. It should benoted that a valid bit L that is used to indicate CQI feedbackinformation in UCI is correlated to a quantity S of absolute indicatorvalues in a CQI set configured through RRC, where L≥log₂(S).

The channel quality indicator set configured by the network device forthe terminal device may be a set including consecutive values in thepreset set specified in the protocol, or the channel quality indicatorset configured by the network device for the terminal device may be aset including nonconsecutive values in the preset set specified in theprotocol.

When indicating the channel quality indicator set to the terminaldevice, the network device may directly indicate an absolute indicatorvalue included in the channel quality indicator set, for example,directly indicate a CQI index included in the channel quality indicatorset. For example, a channel quality indicator set configured by thenetwork device for a terminal device of an edge user is {0, 2, 4, 6, 8,10, 12}, a channel quality indicator set configured by the networkdevice for a terminal device of a center user is {14, 16, 18, 20, 22,24}, and SINR intervals detected by the terminal device of the edge userand the terminal device of the center user are different. Therefore,CQIs of different intervals are configured.

Optionally, a quantity of absolute indicator values in the channelquality indicator set indicated by the network device to the terminaldevice may be specified in the protocol (the quantity specified in theprotocol is a quantity preset in the network device and the terminaldevice), or is configurable. If the quantity of absolute indicatorvalues in the channel quality indicator set is configurable, thequantity may be configured based on a service. For example, a quantityof absolute indicator values in a channel quality indicator setcorresponding to a URLLC service is less than a quantity of absoluteindicator values in a channel quality indicator set corresponding to aneMBB service. Alternatively, the network device configures the quantityof absolute indicator values in the channel quality indicator set basedon a service and/or a channel quality fluctuation status. For example, achannel quality indicator set with a relatively small quantity ofabsolute indicator values is configured for a user at a relatively slowmoving speed or a user in a static state, and a channel qualityindicator set with a relatively large quantity of absolute indicatorvalues is configured for a user at a relatively fast moving speed.

For example, a channel quality indicator set configured by the networkdevice for a terminal device of a URLLC service is {0, 2, 4, 6, 8, . . ., 28, 30}, that is, even-numbered CQI indexes. A channel qualityindicator set configured by the network device for a terminal device ofan eMBB service is {0, 1, 2, . . . , 31} or {6, 8, 10, 12, 14, 16, 17, .. . , 31}. To indicate a channel status at any moment, a relativelylarge SINR interval, namely, a relatively large CQI index range, needsto be configured for the terminal device of the URLLC service. However,considering a limitation of CQI indication signaling overheads on theURLLC service, elements may be uniformly selected from the preset set,but this application is not limited to uniform selection. Because theterminal device of the eMBB service is insensitive to CQI indicationsignaling overheads, a relatively large set may be configured for theterminal device of the eMBB service, and even the entire preset set maybe configured for the terminal device of the eMBB service. If the entirepreset set is configured for the terminal device of the eMBB service,the entire preset set may be configured on the terminal side by default,and no additional signaling is required for indication.

The channel quality indicator set configured by the network device forthe terminal device is a set including consecutive values in the presetset specified in the protocol, or the channel quality indicator setconfigured by the network device for the terminal device is a setincluding elements at equal intervals (for example, one value isselected at intervals of one element, and indices are 3, 5, and 7) inthe preset set specified in the protocol. In this case, signaling (thesignaling may include but is not limited to higher layer signaling, MACCE signaling, user-specific signaling, and the like) used by the networkdevice to indicate the channel quality indicator set to the terminaldevice may indicate only an index of a starting element of the channelquality indicator set in the preset set and a quantity of elementsincluded in the channel quality indicator set, or indicate only an indexof a starting element of the channel quality indicator set in the presetset, and a quantity of elements in the channel quality indicator set isspecified in the protocol. An element in the channel quality indicatorset is an absolute indicator value in the channel quality indicator set.

For example, the quantity of elements in the channel quality indicatorset is specified in the protocol, and the channel quality indicator setconfigured by the network device for the terminal device includesconsecutive absolute indicator values in the preset set specified in theprotocol. If the channel quality indicator set configured by the networkdevice for the terminal device of the edge user is {0, 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11}, 0 is indicated. If the channel quality indicator setconfigured by the network device for the terminal device of the centeruser is {10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21}, 10 isindicated. Optionally, the quantity of elements in the channel qualityindicator set may be bound to a service type (for example, a quantity ofelements included in the channel quality indicator set of the URLLCservice is 8, and a quantity of elements included in the channel qualityindicator set of the eMBB service is 16).

For another example, the quantity of elements in the channel qualityindicator set is specified in the protocol, and the channel qualityindicator set configured by the network device for the terminal deviceincludes elements at equal intervals in the preset set specified in theprotocol, that is, values are selected at equal intervals from thepreset set, and only the index of the starting element is indicated (ifthe channel quality is a CQI, the index is a CQI index). If the channelquality indicator set configured by the network device for the terminaldevice of the edge user is {0, 2, 4, 6, 8, 10}, 0 is indicated. If thechannel quality indicator set configured by the network device for theterminal device of the center user is {10, 12, 14, 16, 18, 20}, 10 isindicated. Optionally, the quantity of elements in the channel qualityindicator set may be bound to a service type (for example, a quantity ofelements included in the channel quality indicator set of the URLLCservice is 8, and a quantity of elements included in the channel qualityindicator set of the eMBB service is 16).

If a manner of selecting channel quality absolute indicator values (thatis, consecutively selecting values or selecting values at equalintervals) from the channel quality indicator set configured by thenetwork device for the terminal device is determined, the network devicemay indicate only a starting location (the starting location may be anindex, for example, a CQI index) and a quantity of absolute indicatorvalues included in the channel quality indicator set (for example, aquantity of included CQI indexes). The starting location and thequantity of absolute indicator values may be independently coded orjointly coded.

For example, if the channel quality indicator set configured by thenetwork device for the terminal device of the edge user is {0, 2, 4, 6,8, 10}, {0, 6} is indicated, where 0 is a starting location, and 6 is aquantity of absolute indicator values included in the channel qualityindicator set. Alternatively, two elements 0 and 6 may be jointly coded,for example, 160 is obtained through calculation according to a treeindication formula. If the channel quality indicator set configured bythe network device for the terminal device of the center user is {10,11, 12, 13, 14, 15, 16, 17, 18, 19, 20}, {10, 11} is indicated, where 10is a starting location, and 11 is a quantity of absolute indicatorvalues included in the channel quality indicator set. Alternatively, twoelements 10 and 11 are jointly coded, for example, 331 is obtainedthrough calculation according to the tree indication formula. The treeindication formula is as follows:if(L _(set)−1)≤└N _(ca)/2┘ thenRIV=N _(ca)(L _(set)−1)+Set_(start)elseRIV=N _(ca)(N _(ca) −L _(Set)+1)+(N _(ca)−1−Set_(start))

where L_(Set)≥1 and shall not exceed N_(ca)−Set_(start)

L_(Set) is a quantity of CQIs in the channel quality indicator set,N_(ca) is a quantity of elements in the preset set, and Set_(start) is astarting location.

If the channel quality indicator set configured by the network devicefor the terminal device includes elements randomly selected from thepreset set specified in the protocol. In other words, there is no rule,signaling (the signaling may include but is not limited to higher layersignaling, MAC CE signaling, user-specific signaling, and the like) forindicating the channel quality indicator set may be used for indicationto the terminal device by using a bitmap. For example, if the preset setincludes 64 absolute indicator values, 64 bits are used for indication.If the channel quality indicator set includes the absolute indicatorvalue, a bit corresponding to the absolute indicator value is set to 1.If the channel quality indicator set does not include the absoluteindicator value, a bit corresponding to the absolute indicator value isset to 0.

For example, the channel quality indicator set configured by the networkdevice for the terminal device of the edge user is {0, 2, 4, 6, 8, 10,12}, and the channel quality indicator set configured by the networkdevice for the terminal device of the center user is {14, 16, 18, 20,22, 24}. In this case, when the bitmap is used for indication to theterminal device, 101010101010000 . . . 0 may be indicated to theterminal device of the edge user, and 000000000000001010101010100 . . .0 may be indicated to the terminal device of the center user.

The terminal device obtains the channel quality indicator set determinedby the network device, where the channel quality indicator set is thepreset set or a subset of the preset set, and the channel qualityindicator set includes a channel quality absolute indicator value. Theterminal device measures channel quality, and sends, to the networkdevice, feedback information corresponding to a channel qualitymeasurement value. A quantity of bits for the feedback information iscorrelated to a quantity of absolute indicator values included in thechannel quality indicator set. For example, as shown in FIG. 9, thepreset set includes 32 absolute indicator values, the channel qualityindicator set configured by the network device for the terminal deviceincludes 16 absolute indicator values (for example, an interval of 0 to15 or an interval of 16 to 31), and the terminal device may provide afeedback by using four-bit feedback information.

After receiving the feedback information sent by the terminal device,the network device needs to determine an absolute indicator valuecorresponding to the feedback information. For example, if the feedbackinformation sent by the terminal device is 1111, an absolute indicatorvalue of 15 or 31 may be indicated. Therefore, the network device needsto obtain the channel quality indicator set preconfigured for theterminal device. For example, if the channel quality indicator setpreconfigured by the network device for the terminal device is 16 to 31,it indicates that the absolute indicator value corresponding to thefeedback information is 31.

In this embodiment of this application, the network device configures achannel quality indicator set exclusive to each terminal device for theterminal device, where the channel quality indicator set includes achannel quality indicator value, the channel quality indicator value isused to indicate channel quality, and the channel quality indicatorvalue is set for channel quality of the terminal device. Therefore, whenfeeding back the channel quality, the terminal device can accuratelyfeed back the channel quality to the network device, thereby improvingaccuracy of a channel quality feedback.

FIG. 10 is a schematic flowchart of a modulation and coding policyindication method according to an embodiment of this application. Themethod is described from a perspective of interaction between a networkdevice and a terminal device, and the method may include but is notlimited to the following steps:

Step S20: The network device determines a modulation and coding schemeMCS level indicator set of the terminal device, where the MCS levelindicator set includes an MCS level indicator value, and the MCS levelindicator value is used to indicate a modulation and coding policy.

Step S21: The network device sends the MCS level indicator set to theterminal device.

Step S22: The terminal device receives the MCS level indicator setdetermined for the terminal device, where the MCS level indicator setincludes an MCS level indicator value, and the MCS level indicator valueis used to indicate a modulation and coding policy.

Step S23: The terminal device stores the MCS level indicator set.

Step S24: The network device sends indication information to theterminal device, where the indication information is used to indicate atarget MCS level indicator value in the MCS level indicator set, and thetarget MCS level indicator value is used to indicate a modulation andcoding policy used by the network device.

Step S25: The terminal device receives the indication information sentby the network device, where the indication information is used toindicate the target MCS level indicator value in the MCS level indicatorset, and the target MCS level indicator value is used to indicate themodulation and coding policy used by the network device.

In this embodiment of this application, different terminal devicesusually work in different SINR intervals. For example, when a terminaldevice is an edge user, the terminal device usually works in arelatively low SINR, for example, −12 dB to −2 dB, and when a terminaldevice is a center user, the terminal device usually works in arelatively high SINR, for example, 15 dB to 25 dB. A range of MCS levelsfor transmitting data by the network device to the edge user is alsodifferent from a range of MCS levels for transmitting data by thenetwork device to the center user. For example, an MCS level used by thenetwork device to transmit data to the edge user is relatively low, andan MCS level used by the network device to transmit data to the centeruser is relatively high. To reduce indication overheads, the networkdevice independently configures an MCS level indicator set for eachterminal device.

Optionally, the MCS level indicator set configured by the network devicefor the terminal device is a preset set or a subset of the preset set,and the preset set may be a set specified in a protocol. FIG. 11A andFIG. 11B may show a preset set according to an embodiment of thisapplication. The preset set includes 64 MCS levels. The network devicemay configure some or all of the 64 MCS levels based on a channelquality status of the terminal device.

For example, an MCS level indicator set configured by the network devicefor the terminal device that is an edge user is 0 to 27 and 58 to 61,and an MCS level indicator set configured by the network device for theterminal device that is a center user is 28 to 57 and 61 to 63. Itshould be noted that indices herein represent MCS levels in FIG. 11A andFIG. 11B, and MCS levels 58 to 63 are used for retransmission. A validbit L that is in DCI and that is used to indicate an MCS level iscorrelated to a quantity S of MCS levels in an MCS level indicator setconfigured through RRC, where L≥log 2(S).

The MCS level indicator set configured by the network device for theterminal device may include consecutive MCS level indicator values (MCSlevels) in the preset set specified in the protocol, or a MCS levelindicator set configured by the network device for the terminal devicemay include nonconsecutive MCS level indicator values (MCS levels) inthe preset set specified in the protocol.

The MCS level indicator set configured by the network device for theterminal device includes consecutive MCS level indicator values in thepreset set specified in the protocol, or the MCS level indicator setconfigured by the network device for the terminal device includes MCSlevel indicator values at equal intervals in the preset set specified inthe protocol (for example, one value is selected at intervals of oneelement, and indices are 3, 5, and 7). In this case, signaling (thesignaling may include but is not limited to higher layer signaling, MACCE signaling, user-specific signaling, and the like) used by the networkdevice to indicate the MCS level indicator set to the terminal devicemay indicate only an index of a starting element of the MCS levelindicator set in the preset set and a quantity of elements included inthe MCS level indicator set, or indicate only an index of a startingelement of the MCS level indicator set in the preset set, and a quantityof elements in the MCS level indicator set is specified in the protocol.An element in the MCS level indicator set is an MCS level indicatorvalue in the MCS level indicator set. Further, optionally, the signalingused by the network device to indicate the MCS level indicator set tothe terminal device may be alternatively used for indication by using atree indication method. The tree indication method is the same as thetree indication method in the embodiment in FIG. 4, and details are notdescribed herein again.

If the MCS level indicator set configured by the network device for theterminal device includes elements randomly selected from the preset setspecified in the protocol. In other words, there is no rule, signaling(the signaling may include but is not limited to higher layer signaling,MAC CE signaling, user-specific signaling, and the like) for indicatingthe MCS level indicator set may be used for indication to the terminaldevice by using a bitmap. For example, if the preset set includes 64absolute indicator values, 64 bits are used for indication. If the MCSlevel indicator set includes the MCS level indicator value, a bitcorresponding to the MCS level indicator value is set to 1. If the MCSlevel indicator set does not include the MCS level indicator value, abit corresponding to the MCS level indicator value is set to 0.

The terminal device obtains and stores the MCS level indicator setconfigured by the network device for the terminal device. When thenetwork device transmits data to the terminal device, the network deviceneeds to indicate the used target MCS level indicator value to theterminal device, where the target MCS level indicator value is used toindicate the modulation and coding policy used by the network device, sothat the terminal device can process the received data according to themodulation and coding policy.

Specifically, optionally, the network device sends the indicationinformation to the terminal device, where the indication information isused to indicate the target MCS level indicator value in the MCS levelindicator set configured for the terminal device. Optionally, thenetwork device may send the indication information to the terminaldevice by using DCI. For example, the MCS level indicator set configuredby the network device for the terminal device is 0 to 27 and 58 to 61.The indication information may be 5 bits, and one type of indicationinformation corresponds to one MCS level indicator value.

The terminal device searches for, based on the MCS level indicator setconfigured by the network device, the target MCS level indicator valuecorresponding to the indication information, where the target MCS levelindicator value is used to indicate the modulation and coding policyused by the network device.

In this embodiment of this application, the network device determinesthe MCS level indicator set exclusive to the terminal device for theterminal device. The MCS level indicator set includes an MCS levelindicator value, and the MCS level indicator value is used to indicate amodulation and coding policy. The MCS level indicator set exclusive tothe terminal device may be a set that is set based on channel quality ofthe terminal device. Subsequently, when indicating the modulation andcoding policy, the network device can improve indication accuracy whilereducing overheads.

The foregoing describes the method in the embodiments of thisapplication in detail, and the following describes an apparatus providedin the embodiments of this application.

FIG. 12 is a schematic diagram of a logical structure of a networkdevice 101 according to an embodiment of this application. The networkdevice 101 may include a processing unit 1011 and a transceiver unit1012.

The processing unit 1011 is configured to determine a channel qualityindicator set of a terminal device, where the channel quality indicatorset includes at least one channel quality indicator value, and thechannel quality indicator value is used to indicate channel quality.

The transceiver unit 1012 is configured to send the channel qualityindicator set to the terminal device.

It should be noted that the processing unit 1011 is configured toperform step S10 in the method embodiment shown in FIG. 4, and thetransceiver unit 1012 is configured to perform step S11 in the methodembodiment shown in FIG. 4.

For specific details, refer to the description of the network deviceside in the foregoing method in FIG. 4. Details are not described hereinagain.

FIG. 13 is a schematic diagram of a physical structure of a networkdevice 102 according to an embodiment of this application. The networkdevice 102 includes a processor 1021, a transceiver 1022, and a memory1023. The processor 1021, the memory 1023, and the transceiver 1022 areinterconnected through a bus.

The memory 1023 includes but is not limited to a random access memory(Random Access Memory, RAM), a read-only memory (Read-Only Memory, ROM),an erasable programmable read-only memory (Erasable Programmable ReadOnly Memory, EPROM), or a compact disc read-only memory (Compact DiscRead-Only Memory, CD-ROM). The memory 1023 is configured to store arelated instruction and data.

The transceiver 1022 may be a communications module or a transceivercircuit, and is configured to transmit information such as data andsignaling between the network device and a terminal device. In thisembodiment of this application, the transceiver 1022 is configured toperform step S11 in the method embodiment shown in FIG. 4.

The processor 1021 may be a controller, a central processing unit(Central Processing Unit, CPU), a general purpose processor, a digitalsignal processor (Digital Signal Processor, DSP), anapplication-specific integrated circuit (Application-Specific IntegratedCircuit, ASIC), a field programmable gate array (Field Programmable GateArray, FPGA) or another programmable logic device, a transistor logicdevice, a hardware component, or a combination thereof. The processor1021 may implement or execute various example logical blocks, modules,and circuits described with reference to content disclosed in theembodiments of this application. Alternatively, the processor 1021 maybe a combination of processors implementing a computing function, forexample, one microprocessor or a combination of microprocessors, or acombination of a DSP and a microprocessor. In this embodiment of thisapplication, the processor 1021 is configured to perform step S10 in theembodiment shown in FIG. 4.

For example, the processor 1021 is configured to determine a channelquality indicator set of a terminal device, where the channel qualityindicator set includes at least one channel quality indicator value, andthe channel quality indicator value is used to indicate channel quality.

The transceiver 1022 is configured to send the channel quality indicatorset to the terminal device.

For specific details, refer to the description of the network deviceside in the foregoing method in FIG. 4. Details are not described hereinagain.

FIG. 14 is a schematic diagram of a logical structure of a terminaldevice 201 according to an embodiment of this application. The terminaldevice 201 may include a transceiver unit 2011 and a processing unit2012.

The processing unit 2012 is configured to obtain a channel qualityindicator set determined by a network device for the terminal device,where the channel quality indicator set includes at least one channelquality indicator value, and the channel quality indicator value is usedto indicate channel quality.

The transceiver unit 2011 is configured to send feedback information tothe network device, where the feedback information is used to indicate atarget channel quality indicator value, the target channel qualityindicator value is a channel quality indicator value in the channelquality indicator set, and the target channel quality indicator value isused to determine current channel quality of a channel.

It should be noted that the transceiver unit 2011 is configured toperform step S13 in the method embodiment shown in FIG. 4, and theprocessing unit 2012 is configured to perform step S12 in the methodembodiment shown in FIG. 4.

For specific details, refer to the description of the terminal deviceside in the foregoing method in FIG. 4. Details are not described hereinagain.

FIG. 15 shows a terminal device 202 according to an embodiment of thisapplication. The terminal device 202 includes a processor 2021, atransceiver 2022, and a memory 2023, and the processor 2021, the memory2023, and the transceiver 2022 are interconnected through a bus.

The memory 2023 includes but is not limited to a RAM, a ROM, an EPROM,or a CD-ROM, and the memory 2024 is configured to store a relatedinstruction and data.

The transceiver 2022 may be a communications module or a transceivercircuit, and is configured to transmit information such as data andsignaling between a network device and the terminal device. In thisembodiment of this application, the transceiver 2022 is configured toperform step S13 in the method embodiment shown in FIG. 4.

The processor 2021 may be a controller, a CPU, a general purposeprocessor, a DSP, an ASIC, an FPGA or another programmable logic device,a transistor logic device, a hardware component, or any combinationthereof. The processor 2021 may implement or execute various examplelogical blocks, modules, and circuits described with reference tocontent disclosed in the embodiments of this application. Alternatively,the processor 2021 may be a combination of processors implementing acomputing function, for example, one microprocessor or a combination ofmicroprocessors, or a combination of a DSP and a microprocessor. In thisembodiment of this application, the processor 2021 is configured toperform step S12 in the embodiment shown in FIG. 4.

For example, the processor 2021 is configured to obtain a channelquality indicator set determined by a network device for the terminaldevice, where the channel quality indicator set includes at least onechannel quality indicator value, and the channel quality indicator valueis used to indicate channel quality.

The transceiver 2022 is configured to send feedback information to thenetwork device, where the feedback information is used to indicate atarget channel quality indicator value, the target channel qualityindicator value is a channel quality indicator value in the channelquality indicator set, and the target channel quality indicator value isused to determine current channel quality of a channel.

For specific details, refer to the description of the terminal deviceside in the foregoing method in FIG. 4. Details are not described hereinagain.

FIG. 16 is a schematic diagram of a logical structure of a networkdevice 301 according to an embodiment of this application. The networkdevice 301 may include a processing unit 3011 and a transceiver unit3012.

The processing unit 3011 is configured to determine a modulation andcoding scheme MCS level indicator set of a terminal device, where theMCS level indicator set includes at least one MCS level indicator value,and the MCS level indicator value is used to indicate a modulation andcoding policy.

The transceiver unit 3012 is configured to send the MCS level indicatorset to the terminal device.

It should be noted that the processing unit 3011 is configured toperform step S20 in the method embodiment shown in FIG. 10, and thetransceiver unit 3012 is configured to perform step S21 in the methodembodiment shown in FIG. 10.

For specific details, refer to the description of the network deviceside in the foregoing method in FIG. 10. Details are not describedherein again.

FIG. 17 is a schematic diagram of a physical structure of a networkdevice 302 according to an embodiment of this application. The networkdevice 302 includes a processor 3021, a transceiver 3022, and a memory3023. The processor 3021, the memory 3023, and the transceiver 3022 areinterconnected through a bus.

The memory 3023 includes but is not limited to a random access memory(Random Access Memory, RAM), a read-only memory (Read-Only Memory, ROM),an erasable programmable read-only memory (Erasable Programmable ReadOnly Memory, EPROM), or a compact disc read-only memory (Compact DiscRead-Only Memory, CD-ROM). The memory 3023 is configured to store arelated instruction and data.

The transceiver 3022 may be a communications module or a transceivercircuit, and is configured to transmit information such as data andsignaling between the network device and a terminal device. In thisembodiment of this application, the transceiver 3022 is configured toperform step S21 in the method embodiment shown in FIG. 10.

The processor 3021 may be a controller, a central processing unit(Central Processing Unit, CPU), a general purpose processor, a digitalsignal processor (Digital Signal Processor, DSP), anapplication-specific integrated circuit (Application-Specific IntegratedCircuit, ASIC), a field programmable gate array (Field Programmable GateArray, FPGA) or another programmable logic device, a transistor logicdevice, a hardware component, or a combination thereof. The processor3021 may implement or execute various example logical blocks, modules,and circuits described with reference to content disclosed in theembodiments of this application. Alternatively, the processor 3021 maybe a combination of processors implementing a computing function, forexample, one microprocessor or a combination of microprocessors, or acombination of a DSP and a microprocessor. In this embodiment of thisapplication, the processor 3021 is configured to perform step S20 in theembodiment shown in FIG. 10.

For example, the processor 3021 is configured to determine a modulationand coding scheme MCS level indicator set of a terminal device, wherethe MCS level indicator set includes at least one MCS level indicatorvalue, and the MCS level indicator value is used to indicate amodulation and coding policy.

The transceiver 3022 is configured to send the MCS level indicator setto the terminal device.

For specific details, refer to the description of the network deviceside in the foregoing method in FIG. 10. Details are not describedherein again.

FIG. 18 is a schematic diagram of a logical structure of a terminaldevice 401 according to an embodiment of this application. The terminaldevice 401 may include a transceiver unit 4011 and a processing unit4012.

The transceiver unit 4011 is configured to receive an MCS levelindicator set determined for the terminal device, where the MCS levelindicator set includes at least one MCS level indicator value, and theMCS level indicator value is used to indicate a modulation and codingpolicy.

The processing unit 4012 is configured to store the MCS level indicatorset.

It should be noted that the transceiver unit 4011 is configured toperform step S22 in the method embodiment shown in FIG. 10, and theprocessing unit 4012 is configured to perform step S23 in the methodembodiment shown in FIG. 10.

For specific details, refer to the description of the terminal deviceside in the foregoing method in FIG. 10. Details are not describedherein again.

FIG. 19 shows a terminal device 402 according to an embodiment of thisapplication. The terminal device 402 includes a processor 4021, atransceiver 4022, and a memory 4023, and the processor 4021, the memory4023, and the transceiver 4022 are interconnected through a bus.

The memory 4023 includes but is not limited to a RAM, a ROM, an EPROM,or a CD-ROM, and the memory 4024 is configured to store a relatedinstruction and data.

The transceiver 4022 may be a communications module or a transceivercircuit, and is configured to transmit information such as data andsignaling between a network device and the terminal device. In thisembodiment of this application, the transceiver 4022 is configured toperform step S22 in the method embodiment shown in FIG. 10.

The processor 4021 may be a controller, a CPU, a general purposeprocessor, a DSP, an ASIC, an FPGA or another programmable logic device,a transistor logic device, a hardware component, or any combinationthereof. The processor 4021 may implement or execute various examplelogical blocks, modules, and circuits described with reference tocontent disclosed in the embodiments of this application. Alternatively,the processor 4021 may be a combination of processors implementing acomputing function, for example, one microprocessor or a combination ofmicroprocessors, or a combination of a DSP and a microprocessor. In thisembodiment of this application, the processor 4021 is configured toperform step S23 in the embodiment shown in FIG. 10.

For example, the transceiver 4022 is configured to receive an MCS levelindicator set determined for the terminal device, where the MCS levelindicator set includes at least one MCS level indicator value, and theMCS level indicator value is used to indicate a modulation and codingpolicy.

The processor 4021 is configured to store the MCS level indicator set.

For specific details, refer to the description of the terminal deviceside in the foregoing method in FIG. 10. Details are not describedherein again.

In an implementation process, steps of the foregoing methods may becompleted by using a hardware integrated logic circuit in the processor,or by using an instruction in a form of software. The steps of themethods disclosed with reference to the embodiments of this applicationmay be directly performed and completed by a hardware processor, or maybe performed and completed by using a combination of hardware in theprocessor and a software unit. The software unit may be located in amature storage medium in the art, such as a random access memory, aflash memory, a read-only memory, a programmable read-only memory, anelectrically erasable programmable memory, or a register. The storagemedium is located in the memory, and the processor executes aninstruction in the memory and completes the steps of the foregoingmethods in combination with hardware in the processor. To avoidrepetition, details are not described herein again.

It should be understood that the term “and/or” in this specificationdescribes only an association relationship for describing associatedobjects and represents that three relationships may exist. For example,A and/or B may represent the following three cases: Only A exists, bothA and B exist, and only B exists. In addition, the character “/” in thisspecification generally indicates an “or” relationship between theassociated objects.

A 5G communications system strives to support higher system performance,more service types, different deployment scenarios, and a wider spectrumrange. The service types mainly include an enhanced mobile broadband(eMBB) service, a massive machine type communication (mMTC) service, anultra-reliable and low latency communications (URLLC) service, amultimedia broadcast multicast service (MBMS), a positioning service,and the like. The deployment scenarios mainly include an indoor hotspotscenario, a dense urban scenario, a rural scenario, an urban macroscenario, a high-speed railway scenario, and the like. The widerspectrum range is mainly a spectrum range up to 100 GHz. In other words,the spectrum range includes a low-frequency part less than 6 GHz and ahigh-frequency part ranging from 6 GHz to 100 GHz.

Compared with a 4G communications system, one feature of the 5Gcommunications system is that a URLLC service is supported. There aremany URLLC service types, for example, industrial control, industrialproduction process automation, human computer interaction, andtelemedicine. To better quantize performance indicators of a URLLCservice to provide a reference input and evaluation criterion fordesigning the 5G system, the 3rd generation partnership project (3GPP)radio access network (RAN) and RAN1 working groups define the followingperformance indicators of the URLLC service.

A latency is a transmission time that is required when a service dataunit (SDU) of a user application layer packet is transmitted from aradio protocol stack layer 2/3 of a transmit end to a radio protocolstack layer 2/3 of a receive end. Both an uplink user plane latencyrequirement and a downlink user plane latency requirement of a URLLCservice are 0.5 ms, and the foregoing requirements are applicable onlywhen neither a base station nor a terminal is in a discontinuousreception (DRX) state. It should be noted that the performancerequirement of 0.5 ms herein means an average latency of a data packet,and is not bound to the following reliability requirement.

Reliability is a success probability that X bits are correctlytransmitted from the transmit end to the receive end in a particulartime (L seconds) in a given channel quality condition. The foregoingtime is also defined as a time that is required when a service data unit(Service Data Unit, SDU) of a user application layer packet istransmitted from a radio protocol stack layer 2/3 of a transmit end to aradio protocol stack layer 2/3 of a receive end. For a URLLC service, atypical requirement is achieving reliability of 99.999% in 1 ms.

It should be noted that the foregoing performance indicator is merely anexample. Specifically, the URLLC service may have different reliabilityrequirements. For example, some extremely hash industrial controlrequires a transmission success probability of 99.9999999% in anend-to-end latency of 0.25 ms.

A system capacity is a maximum throughput that a system can reachwithout user interruption. The user interruption herein means that thesystem cannot meet a reliability requirement in a particular latencyrange.

In a conventional solution, a terminal device indicates channel qualitybetween a network device and the terminal device by using a channelquality indicator (CQI) index corresponding to a BLER. Specifically, theterminal device may feed back CQI indices corresponding to all blockerror rates. However, if a channel environment changes, when the CQIindices corresponding to all the block error rates are fed back in theconventional solution, signaling overheads of feeding back the CQIindices are relatively high.

FIG. 20 is a schematic flowchart of a communication method according toan embodiment of this application.

The communication method is applied to a system that supports at leastone block error rate BLER set, a first BLER set of the at least one BLERset includes a first BLER subset and a second BLER subset, the firstBLER subset includes at least one BLER, and the second BLER subsetincludes at least one BLER.

It should be understood that a BLER in this embodiment of thisapplication may be 10%, 1%, 0.1%, or 0.001%, or may be of another type.This is not limited in this application.

Optionally, the first BLER set may be any one of the at least one BLERset, that is, another BLER set of the at least one BLER set may alsoinclude a first BLER subset and a second BLER subset. This is notlimited in this application.

It should be noted that, in this embodiment of this application, aterminal device determines, as the first BLER subset, a set including atleast one BLER that is in each BLER set and that corresponds to achannel quality parameter absolute value that needs to be sent to anetwork device, that is, BLERs specifically included in first BLERsubsets in different BLER sets may be the same or different.

Optionally, a BLER included in the first BLER set and a BLER included inanother BLER set of the at least one BLER set may be totally the same,or may be partially the same, or may be totally different. This is notlimited in this application.

2001. The terminal device determines a channel quality parametercorresponding to each BLER in the first BLER subset.

The terminal device may determine the channel quality parametercorresponding to each BLER in the first BLER subset in the first BLERset, or may determine channel quality parameters corresponding to allBLERs in all first BLER subsets in all of the at least one BLER setincluded in the system. This is not limited in this application.

Optionally, the channel quality parameter may be a signal tointerference plus noise ratio (Signal to Interference plus Noise Ratio,SINR), or may be a CQI index.

2002. The terminal device sends, to the network device, the channelquality parameter corresponding to each BLER in the first BLER subset.

Correspondingly, the network device receives the channel qualityparameter that corresponds to each BLER in the first BLER subset andthat is sent by the terminal device.

2003. The network device determines, based on the channel qualityparameter corresponding to each BLER in the first BLER subset and atleast one channel quality parameter difference between a channel qualityparameter corresponding to at least one BLER in the second BLER subsetand a channel quality parameter corresponding to at least one BLER inthe first BLER subset, a channel quality parameter corresponding to eachBLER in the second BLER subset.

Specifically, the network device may receive only the channel qualityparameter corresponding to each BLER in the first BLER subset, anddetermine, based on the at least one channel quality parameterdifference between the channel quality parameter corresponding to the atleast one BLER in the second BLER subset and the channel qualityparameter corresponding to the at least one BLER in the first BLERsubset, the channel quality parameter corresponding to the at least oneBLER in the second BLER subset. A channel quality parameter differencebetween channel quality parameters corresponding to two BLERs isbasically kept consistent in a fixed condition. Therefore, in thisembodiment of this application, when a channel environment changes, theterminal device can learn of channel quality parameters corresponding toall BLERs in the first BLER set only by sending a channel qualityparameter corresponding to a BLER in the first BLER subset, so that theterminal device is prevented from sending the channel quality parameterscorresponding to all the BLERs in the first BLER set when the channelenvironment changes, thereby reducing signaling overheads.

It should be understood that the fixed condition herein may be atransmission mode or a moving speed or a channel environment (forexample, an urban environment or a rural environment).

Optionally, the at least one channel quality parameter difference may bea table, a set, or a value.

For example, if the first BLER subset includes only one BLER (a firstBLER is used as an example for description), the network device maydetermine, based on a received channel quality parameter correspondingto the first BLER and a channel quality parameter difference between thechannel quality parameter corresponding to the first BLER and thechannel quality parameter corresponding to the at least one BLER in thesecond BLER subset, the channel quality parameter corresponding to theat least one BLER in the second BLER subset.

Specifically, as shown in Table 1, a BLER included in the first BLERsubset may be 10%, and a BLER included in the second BLER subset may be1%, 0.1%, 0.01% or 0.001%. The network device may receive a CQI thatcorresponds to 10% and that is sent by the terminal device, anddetermine, based on this value and CQI level differences in Table 1,CQIs that respectively correspond to 1%, 0.1%, 0.01%, and 0.001%.

TABLE 1 BLER CQI level difference SINR difference 10%-1%   0.5 0.510%-0.1%  1 1 10%-0.01% 1.5 1.5  10%-0.001% 2 2

It should be noted that a decimal in the table indicates that anequivalent code rate converted from the decimal meets a target BLERrequirement. For example, the first BLER corresponds to a CQI 1, and adifference between the CQI 1 corresponding to the first BLER and a CQI 2corresponding to a second BLER is 0.5. The CQI 1 corresponds to 16QAMand a code rate 1 of 0.5, and a CQI level adjacent to the CQI 1corresponds to 16QAM and a code rate 2 of 0.75. In this case, the CQI 2corresponds to 16QAM and a code rate of 0.5+(0.75-0.5)×0.5 (Code Rate1+(Code Rate 2−Code Rate 1)×CQI Level Difference).

It should be noted that the first BLER subset is for the convenience ofdescribing absolute values of channel quality parameters that need to befed back for these BLERs, and there is no other limitation.

For example, the first BLER set may include only the first BLER and thesecond BLER. In this way, the network device may determine, based on thereceived channel quality parameter corresponding to the first BLER and achannel quality parameter difference between the channel qualityparameter corresponding to the first BLER and a channel qualityparameter corresponding to the second BLER, the channel qualityparameter corresponding to the second BLER.

Optionally, in this embodiment of this application, the at least onechannel quality parameter difference may be specified in a protocol, ormay be sent by the terminal device to the network device in advance.This is not limited in this application.

Optionally, the terminal device may report the at least one channelquality parameter difference periodically or in real time.

Optionally, when the network device requires a channel quality parameterdifference, the network device may send a channel quality parameterrequest to the terminal device, to trigger the terminal device to reportthe channel quality parameter difference, thereby avoiding a resourcewaste.

Optionally, the terminal device may report only one channel qualityparameter difference, and another channel quality parameter differenceis obtained through interpolation, thereby further reducing signalingoverheads. When only a channel quality parameter differencecorresponding to two BLERs exists in a table in the followingembodiment, channel quality parameter differences corresponding to aplurality of groups of BLERs may be obtained through interpolation. Toavoid repetition, details are not described in the following embodiment.

For example, as shown in Table 2, the terminal device reports only a CQIlevel difference between a CQI corresponding to 10% and a CQIcorresponding to 0.001% in a same channel environment. If the terminaldevice receives a CQI 1 corresponding to 10%, the terminal device maydetermine, based on Table 2, a CQI 2 corresponding to 0.001%. Theterminal device may further determine the CQI level differences in Table1 based on 10%, 0.001%, the CQI 1, and the CQI 2 through interpolation.

TABLE 2 BLER CQI level difference 10%-0.001% 2

Optionally, if the system includes at least two BLER sets, CQI levelscorresponding to all BLERs in the at least two BLER sets may bedifferent from each other. In this way, a CQI level difference may beprecisely a channel quality parameter difference in an SINR, therebyimproving accuracy of determining a channel quality parametercorresponding to a BLER in the second BLER subset.

Optionally, CQI level differences corresponding to different BLERs maybe different in different transmission modes. For example, as shown inTable 3, there may be a plurality of values of a channel qualitydifference between channel quality corresponding to two BLERs, and eachdifference corresponds to one CQI level difference index.

TABLE 3 CQI level CQI level CQI level CQI level difference differencedifference difference BLER 10^((−n)) index 0 index 1 index 2 index 4 1 00 0 0 2 0 1 2 3 3 1 2 3 4 4 2 3 5 7 5 2 4 6 8

For example, Table 4 or Table 5 shows channel quality parameterdifferences of channel quality parameters separately corresponding topairs of BLERs in different CQIs.

TABLE 4 CQI level difference CQI 1 CQI 2 CQI 3 CQI 4 CQI 5 CQI 6 CQI 7CQI 8 10%-0.001% 2 2 2 2 2 3 3.5 4

TABLE 5 CQI level difference CQI 1 CQI 2 CQI 3 CQI 4 CQI 5 CQI 6 CQI 7CQI 8 10%-1%  0.5 0.5 0.5 0.5 0.5 0.8 0.5 0.9  1%-0.1% 0.5 0.5 0.5 0.50.5 0.8 0.8 1 0.1%-0.01% 0.5 0.5 0.5 0.5 0.5 0.8 1 1 0.01%-0.001% 0.50.5 0.5 0.5 0.5 0.8 1 1

It should be understood that CQI levels in this embodiment of thisapplication may be all or some of CQI levels defined in the protocol.Table 4 and Table 5 are merely described by using only eight CQI levelsas an example. However, this application is not limited thereto.

It should be further understood that in Table 5, when a CQI level is aCQI 1, a corresponding BLER set may include 10%, 1, 0.1%, 0.01%, and0.001%. In this case, CQI level differences may be CQI level differencescorresponding to a column in which the CQI 1 is located in Table 5. Ifit is learned that BLER=10% corresponds to the CQI 1, a CQIcorresponding to BLER=1% may be calculated as follows: CQI 1+(CQI 2−CQI1)+0.5).

Optionally, the terminal device may feed back channel quality parameterdifferences of channel quality parameters corresponding to pairs ofBLERs only in some of the CQI levels, thereby reducing signalingoverheads.

For example, as shown in Table 4, the terminal device may feed backchannel quality parameter differences between a channel qualityparameter corresponding to 10% and a channel quality parametercorresponding to 0.001% only in a CQI 5, a CQI 6, a CQI 7, and a CQI 8.

Optionally, the some of the CQI levels may be odd-numbered CQI levels oreven-numbered CQI levels, CQI levels at coarse granularities, or sampledCQI levels. The sampled CQI levels may be uniformly sampled CQI levelsor nonuniformly sampled CQI levels. As CQI levels increase, a differencebetween CQI level differences corresponding to adjacent CQI levels islarger, and uniform CQI level differences may be obtained throughnon-uniform sampling, thereby reducing signaling overheads.

Optionally, if the system includes at least two BLER sets, the at leasttwo BLER sets may correspond to a plurality of code rates (coderate). Inthis case, a CQI level difference can be more accurate, therebyimproving accuracy of determining a channel quality parametercorresponding to a BLER in the second BLER subset.

For example, the terminal device may alternatively feed back CQI leveldifferences of CQIs corresponding to pairs of BLERs in different coderates. When Coderate=0.1, an SINR difference between a CQI correspondingto BLER=1 and a CQI corresponding to BLER=0.0001 is 2 db, and acorresponding CQI level difference is 1. When Coderate=0.9, an SINRdifference between a CQI corresponding to BLER=1 and a CQI correspondingto BLER=0.0001 is 4 dB, and a corresponding CQI level difference is 2.

It should be noted that, actually, there is a correspondence amongmodulation, a code rate, and a CQI level. For example, if modulation isQPSK, Coderate=0.1 indicates that a corresponding CQI level of 0, ifmodulation is QPSK, Coderate=0.2 indicates that a corresponding CQIlevel is 1, and so on.

Optionally, BLER-SINR slope values of different terminal devices aredifferent. Therefore, as shown in FIG. 21, independent channel qualityparameter differences may be used for different terminal devices.

Optionally, if the system includes at least two BLER sets, BLERs in theat least two BLER sets may correspond to a plurality of transmissionmodes. In this way, an SINR difference may be precisely an SINRdifference in a transmission mode, thereby improving accuracy ofdetermining a channel quality parameter corresponding to a BLER in thesecond BLER subset.

Optionally, the transmission modes include an antenna port configurationand/or a multiple-input multiple-output (Multiple Input Multiple Output,MIMO) preprocessing mode.

It should be understood that the antenna port configuration may bespecifically ix (that is, one transmit port and one receive port), 1×2,2×2 or the like. The preprocessing mode may include at least one oftransmit diversity, precoding, and beamforming.

It should be further understood that MIMO includes single-inputsingle-output (Single Input Single Output, SISO), single-inputmultiple-output (Single Input Multiple Output, SIMO), and multiple-inputsingle-output (Multiple Input Single Output, MISO).

For example, Table 6 shows CQI level differences between a CQI levelcorresponding to a BLER of 10% and a CQI level corresponding to a BLERof 0.001% in different transmission modes.

TABLE 6 CQI level Transmission Transmission difference mode 1 mode 210%-0.001% 1 3

Optionally, CQI level differences corresponding to different BLERs indifferent transmission modes may be different. For example, as shown inTable 7 and Table 8, there may be a plurality of values of a channelquality difference between channel quality corresponding to two BLERs.

Optionally, the network device may select a proper CQI level differencebased on a transmission mode.

Optionally, the terminal device may further send indication informationto the network device, where the indication information is used by thenetwork device to determine one CQI level difference from a plurality ofCQI level differences. In the following embodiment, when a channelquality parameter includes a plurality of values, one of the pluralityof values may be determined according to the indication information sentby the terminal device. To avoid repetition, details are not describedin the following embodiment.

TABLE 7 BLER CQI level difference 10%-0.001% 1, 2, 3, 4

TABLE 8 BLER CQI level difference 10%-1%   0.5, 2.5, 3.5, 6.5 10%-0.1% 1, 3, 5, 7 10%-0.01% 1.5, 3.5, 5.5, 7.5  10%-0.001% 2, 4, 6, 8

Optionally, if the system includes at least two BLER sets, in thisembodiment of this application, each of the at least two BLER sets maybe more specifically divided based on a CQI level and a transmissionmode.

For example, as shown in Table 9, a transmission mode 1 and a CQI 1correspond to one BLER set.

TABLE 9 Transmission mode 1 Transmission mode 2 SINR difference (db) CQI1 CQI 2 CQI 3 CQI 4 CQI 1 CQI 2 CQI 3 CQI 4 10%-1%  0.5 0.8 0.5 0.9 0.50.5 0.5 0.5  1%-0.1% 0.5 0.8 0.8 1 0.5 0.5 0.5 0.5 0.1%-0.01% 0.5 0.8 11 0.5 0.5 0.5 0.5 0.01%-0.001% 0.5 0.8 1 1 0.5 0.5 0.5 0.5

Optionally, modulation and coding differences corresponding to pairs ofBLERs may also be determined by using an SINR difference.

For example, as shown in Table 10 or Table 11, an SINR differencebetween an SINR corresponding to BLER=10% and an SINR corresponding toBLER=0.001% is 2.

TABLE 10 BLER SINR difference 10%-0.001% 4

TABLE 11 BLER SINR difference 10%-1%   0 10%-0.1%  1 10%-0.01% 2 10%-0.001% 4

Similarly, as shown in Table 12 or Table 13, an SINR difference may alsoinclude a plurality of values in different transmission modes.

TABLE 12 BLER SINR difference 10%-0.001% 1, 2, 4, 6, 8

TABLE 13 BLER SINR difference 10%-1% 0, 1 10%-0.1% 1, 2 10%-0.01% 1, 2,3 10%-0.001% 2, 3, 4

Optionally, in this embodiment of this application, for example, asshown in Table 14, Table 15, and Table 16, each BLER set may be morespecifically divided.

TABLE 14 SINR difference CQI 1 CQI 2 CQI 3 CQI 4 CQI 5 CQI 6 CQI 7 CQI 810%-1%  0 0 0 0 0 0 0 1  1%-0.1% 1 1 1 0 0 1 1 1 0.1%-0.01% 0 0 0 1 1 11 1 0.01%-0.001% 1 1 1 1 1 1 1 1

TABLE 15 SINR difference CQI 1 CQI 2 CQI 3 CQI 4 CQI 5 CQI 6 CQI 7 CQI 810%-1%   0 0 0 0 0 0 0 1 10%-0.1%  0 0 0 1 1 1 1 2 10%-0.01% 1 1 1 2 2 22 3  10%-0.001% 1 1 1 2 2 2 3 3

TABLE 16 SINR difference CQI 1 CQI 2 CQI 3 CQI 4 CQI 5 CQI 6 CQI 7 CQI 810%-1%   [0.1] [0.1] [0.1] [0.1] [0.1] [0.1] [0.1] [1.2] 10%-0.1%  [0.1][0.1] [0.1] [1.2] [1.2] [1.2] [1.2] [2.3] 10%-0.01% [1.2] [1.2] [1.2][2.3] [2.3] [2.3] [2.3] [3.4]  10%-0.001% [1.2] [1.2] [1.2] [2.3] [2.3][2.3] [2.3] [3.4]

Optionally, a BLER set of at least one BLER set may correspond to aplurality of transmission modes. For example, Table 17 shows SINRdifferences corresponding to two BLERs in different transmission modes,and Table 18 may show SINR differences that correspond to two BLERs andthat are affected by another condition.

TABLE 17 SINR difference Transmission mode 1 Transmission mode 210%-0.001% 2 5

TABLE 18 SINR difference Transmission mode 1 Transmission mode 210%-0.001% 2, 4 5, 7

Optionally, as shown in Table 19 and Table 20, each BLER set of at leastone BLER set may be divided based on a transmission mode and a CQIlevel.

TABLE 19 Transmission mode 1 Transmission mode 2 SINR difference CQI 1CQI 2 CQI 3 CQI 4 CQI 1 CQI 2 CQI 3 CQI 4 10%-1%  1 1 1 1 0.5 0.5 0.50.5  1%-0.1% 1 1 1 1 0.5 0.5 0.5 0.5 0.1%-0.01% 1 1 1 1 0.5 0.5 0.5 0.50.01%-0.001% 1 1 1 1 0.5 0.5 0.5 0.5

TABLE 20 Transmission mode 1 Transmission mode 2 SINR difference CQI 1CQI 2 CQI 3 CQI 4 CQI 1 CQI 2 CQI 3 CQI 4 10%-1%  1.2 1.2 1.2 1.2 0.10.1 0.1 0.1  1%-0.1% 1.2 1.2 1.2 1.2 0.1 0.1 0.1 0.1 0.1%-0.01% 1.2 1.21.2 1.2 0.1 0.1 0.1 0.1 0.01%-0.001% 1.2 1.2 1.2 1.2 0.1 0.1 0.1 0.1

Optionally, the terminal device may further send an index value of achannel quality parameter difference to the network device, where theindex value of the channel quality parameter difference is in aone-to-one correspondence with the channel quality parameter difference.The network device may determine the corresponding channel qualityparameter difference based on the index value of the channel qualityparameter difference.

Specifically, the network device may learn of a plurality of channelquality parameter differences between channel quality parameterscorresponding to two BLERs, but cannot specifically learn whichdifference is a current difference between the channel qualityparameters corresponding to the two BLERs. In this case, the networkdevice may determine, based on the index value that is of a channelquality parameter difference and that is sent by the terminal device,which one of the plurality of differences between the channel qualityparameters corresponding to the two BLERs is specifically the channelquality parameter difference, so that the channel quality parametercorresponding to each BLER in the second BLER subset can be accuratelydetermined, thereby improving accuracy of determining channel quality.

Optionally, if a channel quality parameter is a CQI level, a CQI leveldifference reported by the terminal device may be represented by using aCQI index.

Specifically, a correspondence between a CQI level difference and a CQIlevel difference index is shown in Table 21. For example, if theterminal device determines that a CQI level difference corresponding totwo BLERs is 4, the terminal device may send a CQI level differenceindex of 3 to the network device, so that the network device candetermine, based on the CQI level difference index of 3, that the CQIlevel difference corresponding to the two BLERs is 4.

TABLE 21 CQI level difference index 0 1 2 3 CQI level difference 0 1 2 4

Optionally, the network device sends a channel quality parameter requestto the terminal device, where the channel quality parameter request maybe used to request at least one channel quality parameter differencebetween a channel quality parameter corresponding to each BLER in asecond BLER subset in a BLER set of the at least one BLER set includedin the system and a channel quality parameter corresponding to at leastone BLER in a first BLER subset. Correspondingly, the terminal devicereports, to the network device according to the channel qualityparameter request, the at least one channel quality parameter differencerequested by using the channel quality parameter request.

Optionally, the network device may use higher layer signaling orphysical layer signaling to carry the channel quality parameter request.

For example, the network device may use higher layer signaling orphysical layer signaling to carry a channel quality parameter requestthat is used to request the at least one channel quality parameterdifference between the channel quality parameter corresponding to eachBLER in the second BLER subset in the first BLER set and the channelquality parameter corresponding to the at least one BLER in the firstBLER subset. The channel quality parameter request may be used torequest the terminal device to report a CQI level differencecorresponding to BLER=10% and BLER=0.001% in the transmission method 1and/or in an SINR.

Optionally, the channel quality parameter request may be further used torequest a specific quantity of channel quality parameter differencescorresponding to the at least one BLER.

For example, the channel quality parameter request may be used torequest CQI level differences corresponding to BLERs in four SINRs. Inthis way, after receiving the foregoing higher layer signaling or theforegoing physical layer signaling, the terminal device reports four CQIlevel differences of 0, 1, 2, and 3 that correspond to BLER=10% andBLER=0.001%. The four CQI level differences may separately correspond todifferent SINRs.

Optionally, the network device may request, by using the channel qualityparameter request, a channel quality parameter difference between BLERsin some of BLER sets in the system.

For example, the channel quality parameter request may be used torequest the terminal device to report four CQI level differencescorresponding to BLER=10% and BLER=0.001%, BLER=10% and BLER=0.01%,BLER=10% and BLER=0.1%, and BLER=10% and BLER=1%.

Optionally, the network device sends a channel quality parameter requestto the terminal device, where the channel quality parameter request maybe used to request a channel quality parameter difference between achannel quality parameter corresponding to at least one BLER in a firstBLER subset in each of the at least one BLER set and a channel qualityparameter corresponding to each BLER in a second BLER subset.Correspondingly, the terminal device reports, to the network deviceaccording to the channel quality parameter request, the at least onechannel quality parameter difference requested by using the channelquality parameter request.

Optionally, the network device may use higher layer signaling orphysical layer signaling to carry the channel quality parameter request,or may report all CQI level difference sets by using a semi-staticconfiguration.

Therefore, according to the method for determining channel quality inthis embodiment of this application, the network device may receive achannel quality parameter that corresponds to a BLER in the first BLERsubset in the first BLER set and that is sent by the terminal device,and determine, based on channel quality parameters corresponding to someBLERs in the first BLER subset and the channel quality parameterdifference between the channel quality parameter corresponding to eachBLER in the second BLER subset and the channel quality parametercorresponding to the at least one BLER in the first BLER subset, channelquality parameters corresponding to all BLERs in the second BLER subset.In other words, the network device can determine channel qualityparameters corresponding to all BLERs in the first BLER set, andtherefore the terminal device does not need to send the channel qualityparameters corresponding to all the BLERs in the first BLER set, therebyreducing signaling overheads.

Table 22 shows a correspondence between a CQI index and spectrumefficiency (Efficiency) in a conventional solution. In this conventionalsolution, 16 states may be represented by using 4 bits, and lowestspectrum efficiency corresponding to a CQI index is 0.1523, that is, amain channel condition interval of a user can be covered.

TABLE 22 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range (out of range) 1 QPSK 78 0.1523 2 QPSK193 0.3770 3 QPSK 449 0.8770 4 16QAM 378 1.4766 5 16QAM 490 1.9141 616QAM 616 2.4063 7 64QAM 466 2.7305 8 64QAM 567 3.3223 9 64QAM 6663.9023 10 64QAM 772 4.5234 11 64QAM 873 5.1152 12 256QAM 711 5.5547 13256QAM 797 6.2266 14 256QAM 885 6.9141 15 256QAM 948 7.4063

FIG. 22 is a schematic flowchart of a communication method according toan embodiment of this application.

2201. A terminal device determines indication information based on acorrespondence table, where the indication information is used toindicate at least one channel quality indicator CQI index, thecorrespondence table includes N CQI indexes, M modulation schemes, and Kcode rate parameters, at least one of the N CQI indexes corresponds toone type of modulation scheme, K of the N CQI indexes are in aone-to-one correspondence with the K code rate parameters, and a productof a code rate corresponding to a first CQI index of the N CQI indexesand a modulation order of a modulation scheme corresponding to the firstCQI index is a value greater than 0 and less than 0.0781, where CodeRate Parameter=Code Rate×1024, N>M, N≥K, and N, K, and M are allpositive integers.

It should be noted that, the product of the code rate corresponding tothe first CQI index of the N CQI indexes and the modulation order of themodulation scheme corresponding to the first CQI index is greater than 0means there is one of the N CQI indexes meets this condition, instead ofa specific CQI index.

Specifically, the correspondence table may be shown in Table 23, and aCQI index may correspond to a reserved value.

Optionally, the spectrum efficiency, the modulation scheme, and the coderate parameter meet the following relationship: SpectrumEfficiency=Modulation Order of Modulation Scheme×Code Rate.

TABLE 23 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 2 0.0039 2 QPSK 4 0.0078 3 QPSK8 0.0156 4 QPSK 16 0.0312 5 QPSK 40 0.0781 6 QPSK 78 0.1523 7 QPSK 1200.2344 8 QPSK 193 0.3770 9 QPSK 308 0.6016 10 QPSK 449 0.8770 11 QPSK602 1.1758 12 16QAM 378 1.4766 13 16QAM 490 1.9141 14 16QAM 616 2.406315 64QAM 466 2.7305 16 64QAM 567 3.3223 17 64QAM 666 3.9023 18 64QAM 7724.5234 19 64QAM 873 5.1152 20 64QAM 948 5.5547 21 256QAM 711 5.5547 22256QAM 797 6.2266 23 256QAM 885 6.9141 24 256QAM 948 7.4063 25 ReservedReserved Reserved 26 Reserved Reserved Reserved 27 Reserved ReservedReserved 28 Reserved Reserved Reserved 29 Reserved Reserved Reserved 30Reserved Reserved Reserved 31 Reserved Reserved Reserved

Optionally, the channel quality indication information may include morethan 4 bits, and values of the bits may represent more than 16 states.

For example, in Table 23, 5 bits represent 32 states, and the 32 statesmay include a reserved (reserved) state.

It should be understood that spectrum efficiency less than 0.0781 inthis embodiment of this application may be a value other than those inTable 23. This is not limited in this application.

Optionally, the K code rate parameters include a value greater than 0and less than 40.

For example, as shown in Table 25, a code rate value may be 16, 8, or 4.It should be understood that a code rate value greater than 0 and lessthan 40 in this embodiment of this application may be another value.This is not limited in this application.

Optionally, the N CQI indexes in the correspondence table are arrangedin ascending order, products of modulation orders of modulation schemescorresponding to all of the first P CQI indexes of the N CQI indexes andcode rates corresponding to all of the first P CQI indexes are arrangedin ascending order, and a product of a modulation order of a modulationscheme corresponding to a (P+h)^(th) CQI index and a code ratecorresponding to the (P+h)^(th) CQI index is less than a product of amodulation order of a modulation scheme corresponding to a P^(th) CQIindex and a code rate corresponding to the P^(th) CQI index, whereN>P+h, h is a value ranging from 1 to N−X, and X>P.

Specifically, a spectrum efficiency value less than 0.0781 thatcorresponds to a CQI index may be arranged behind a maximum spectrumefficiency value, so that the terminal device can determine, asrequired, a quantity of bits included in the channel quality indicationinformation.

For example, as shown in Table 24, when a quantity of bits in thechannel quality indication information is limited, 4 bits are used torepresent 16 states. If a user needs to cover an area in a bad channelcondition, 5 bits are used to cover all states in Table 24.

TABLE 24 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 16 0.1523 2 QPSK 40 0.3770 3QPSK 78 0.8770 4 16QAM 378 1.4766 5 16QAM 490 1.9141 6 16QAM 616 2.40637 64QAM 466 2.7305 8 64QAM 567 3.3223 9 64QAM 666 3.9023 10 64QAM 7724.5234 11 64QAM 873 5.1152 12 256QAM 711 5.5547 13 256QAM 797 6.2266 14256QAM 885 6.9141 15 256QAM 948 7.4063 16 QPSK 2 0.0039 17 QPSK 4 0.007818 QPSK 8 0.0156 19 QPSK 16 0.0312 20 QPSK 40 0.0781 21 ReservedReserved Reserved 22 Reserved Reserved Reserved 23 Reserved ReservedReserved 24 Reserved Reserved Reserved 25 Reserved Reserved Reserved 26Reserved Reserved Reserved 27 Reserved Reserved Reserved 28 ReservedReserved Reserved 29 Reserved Reserved Reserved 30 Reserved ReservedReserved 31 Reserved Reserved Reserved

Optionally, spectrum efficiency corresponding to CQI indexes that aresequentially arranged behind the P^(th) CQI index may be arranged inascending order.

For example, spectrum efficiency corresponding to CQI indexes of 16 to20 shown in Table 24 gradually decreases as the CQI indexes increase,that is, decreases from 0.0039 to 0.0781.

Optionally, the correspondence table may be a part selected from theforegoing table, that is, a total quantity of states is reduced, therebyreducing signaling overheads. For example, details are shown in Table 25and Table 26:

TABLE 25 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 4 0.00781 2 QPSK 16 0.0312 3QPSK 78 0.1523 4 QPSK 449 0.8770 5 16QAM 616 2.4063 6 64QAM 772 4.5234 7256QAM 797 6.2266 8 Reserved Reserved Reserved 9 Reserved ReservedReserved 10 Reserved Reserved Reserved 11 Reserved Reserved Reserved 12Reserved Reserved Reserved 13 Reserved Reserved Reserved 14 ReservedReserved Reserved 15 Reserved Reserved Reserved

TABLE 26 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 78 0.1523 2 QPSK 449 0.8770 316QAM 378 1.4766 4 16QAM 616 2.4063 5 64QAM 666 3.9023 6 64QAM 8735.1152 7 256QAM 797 6.2266

Optionally, the network device may send higher layer signaling to theterminal device, where the higher layer signaling indicates thecorrespondence table. Specifically, the terminal device and the networkdevice may agree on Table 23, Table 24, Table 25 or Table 26. Thenetwork device may determine a to-be-used table based on a service or achannel environment, and send the higher layer signaling to indicate theto-be-used correspondence table. Optionally, the terminal device and thenetwork device may agree on a default table or some of correspondencesin a table. If the network device determines that a channel qualityindication range needs to be changed, that is, only one of a pluralityof tables or some of correspondences in a table are required, thenetwork device sends the higher layer signaling to the terminal deviceto indicate a table or some of correspondences in a table. In this way,when the terminal device uses the table indicated by the network device,an indication requirement of a current channel environment can be met,and signaling overheads can be reduced.

2202. The terminal device sends the indication information to thenetwork device. Correspondingly, the network device receives theindication information.

2203. The network device determines, according to the indicationinformation, the modulation and coding scheme corresponding to the atleast one CQI index.

Optionally, the network device may determine, based on the at least oneCQI index indicated by the indication information and the correspondencetable, the modulation and coding scheme corresponding to the at leastone CQI index.

Optionally, the network device may determine each element in thecorrespondence table according to a protocol agreement, or determineeach element in the correspondence table based on the correspondencetable previously configured for the terminal.

Optionally, at least two CQI indexes are in a one-to-one correspondencewith at least two modulation schemes.

Optionally, in modulation schemes corresponding to all CQI indices inthe correspondence table, a quantity of QPSK modulation schemes is thelargest or a quantity of 64QAM modulation schemes is the largest, or a256 QAM modulation scheme is included.

For example, Table 27 covers low and medium SINRs (that is, a quantityof QPSK modulation schemes is relatively large) and can cover 64QAM, andis widely applied.

TABLE 27 CQI Modulation scheme Code rate (code index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 4 0.0078 2 QPSK 8 0.0156 3 QPSK16 0.0312 4 QPSK 40 0.0781 5 QPSK 78 0.1523 6 QPSK 120 0.2344 7 QPSK 1930.3770 8 QPSK 308 0.6016 9 QPSK 449 0.8770 10 QPSK 602 1.1758 11 16QAM378 1.4766 12 16QAM 616 2.4063 13 64QAM 567 3.3223 14 64QAM 772 4.523415 64QAM 948 5.5547

For another example, Table 28 covers low, medium, and high SINRs (mainSINRs), that is, a high CQI level corresponds to a high SINR, and a lowCQI level corresponds to a low SINR. In other words, transmissionefficiency of the user can be ensured, and robust transmission of theuser can be ensured.

TABLE 28 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 78 0.1523 2 QPSK 120 0.2344 3QPSK 193 0.3770 4 QPSK 308 0.6016 5 QPSK 449 0.8770 6 QPSK 602 1.1758 716QAM 378 1.4766 8 16QAM 490 1.9141 9 16QAM 616 2.4063 10 64QAM 4662.7305 11 64QAM 567 3.3223 12 64QAM 666 3.9023 13 64QAM 772 4.5234 1464QAM 873 5.1152 15 64QAM 948 5.5547

For another example, as shown in Table 29, Table 29 covers medium andhigh SINRs, CQI levels in a low-SINR interval are sparse, and CQI levelsin a high-SINR interval are dense. This is applicable to a user withrelatively good channel quality, and improves transmission efficiency.

TABLE 29 Modulation scheme Code rate (code CQI index (Modulation) rate)× 1024 Efficiency 0 Out of range 1 QPSK 78 0.1523 2 QPSK 308 0.6016 3QPSK 602 1.1758 4 16QAM 378 1.4766 5 16QAM 490 1.9141 6 16QAM 616 2.40637 64QAM 466 2.7305 8 64QAM 567 3.3223 9 64QAM 666 3.9023 10 64QAM 7724.5234 11 64QAM 873 5.1152 12 256QAM 711 5.5547 13 256QAM 797 6.2266 14256QAM 885 6.9141 15 256QAM 948 7.4063

Optionally, the network device may determine a correspondence betweeneach CQI index and a modulation scheme in Table 27, Table 28, and Table29 according to a protocol agreement, or the network devicepreconfigures a correspondence between each CQI index and a modulationscheme in Table 27, Table 28, and Table 29 for the terminal device.

Therefore, in this embodiment of this application, the terminal devicedetermines the indication information based on the correspondence table,where the indication information is used to indicate the at least onechannel quality indicator CQI index, the correspondence table includesthe N CQI indexes, the M modulation schemes, and the K code rateparameters, the at least one of the N CQI indexes corresponds to onetype of modulation scheme, the K of the N CQI indexes are in aone-to-one correspondence with the K code rate parameters, and theproduct of the code rate corresponding to the first CQI index of the NCQI indexes and the modulation order of the modulation schemecorresponding to the first CQI index is a value greater than 0 and lessthan 0.0781, where Code Rate Parameter=Code Rate×1024, N>M, N≥K, and N,K, and M are all positive integers; and the terminal device sends theindication information, so that the network device determines, accordingto the indication information, the modulation scheme corresponding tothe at least one CQI index. In other words, this application can beapplied to a system that requires spectrum efficiency lower than 0.0781,that is, an area in a bad channel condition is covered, to ensure that auser can perform communication on a deep fading channel.

FIG. 23 is a schematic flowchart of a communication method according toan embodiment of this application.

2301. A network device determines indication information based on acorrespondence table, where the indication information is used toindicate at least one modulation and coding scheme (Modulation andCoding Scheme, MCS) index value, the correspondence table includes N MCSindexes, M modulation schemes, and K code rate parameters, at least oneof the N MCS indexes corresponds to one type of modulation scheme, K ofthe N MCS indexes are in a one-to-one correspondence with the K coderate parameters, and a product of a code rate corresponding to a firstMCS index of the N MCS indexes and a modulation order of a modulationscheme corresponding to the first MCS index is a value greater than 0and less than 0.0781, where Code Rate Parameter=Code Rate×1024, N>M,N≥K, and N, K, and M are all positive integers.

For example, details are shown in Table 30 and Table 31:

TABLE 30 Code MCS index Modulation scheme (Modulation) rate (code rate)× 1024 0 2 78 1 2 120 2 2 193 3 2 308 4 2 449 5 2 602 6 4 378 7 4 434 84 490 9 4 553 10 4 616 11 4 658 11 4 658 12 6 466 13 6 517 14 6 567 15 6616 16 6 666 17 6 719 18 6 772 19 6 822 20 6 873 21 8 683 22 8 711 23 8754 24 8 797 25 8 841 26 8 885 27 8 917 28 2 Reserved 29 4 30 6 31 8

TABLE 31 Code MCS index Modulation scheme (Modulation) rate (code rate)× 1024 0 2 4 1 2 8 2 2 16 3 2 32 4 2 78 5 2 193 6 2 449 7 4 378 8 4 4349 4 490 10 4 553 11 4 658 12 8 797 13 8 948

Optionally, the K code rate parameters include a value greater than 0and less than 40.

Optionally, as shown in Table 32, the N MCS indexes in thecorrespondence table are arranged in ascending order, spectrumefficiency corresponding to the first P MCS indexes of the N MCS indexesis arranged in ascending order, and spectrum efficiency corresponding toa (P+h)^(th) MCS index is less than spectrum efficiency corresponding toa P^(th) MCS index, where N>P+h, and h=1, 2, . . . .

TABLE 32 Code MCS index Modulation scheme (Modulation) rate (code rate)× 1024 0 2 120 1 2 193 2 2 308 3 2 449 4 2 602 5 4 378 6 4 434 7 4 490 84 553 9 4 616 10 4 658 11 6 466 12 6 517 13 6 567 14 6 616 15 6 666 16 6719 17 6 772 18 6 822 19 6 873 20 8 683 21 8 711 22 8 754 23 8 797 24 8841 25 8 885 26 8 917 27 8 948 28 2 Reserved 29 4 Reserved 30 6 Reserved31 8 Reserved 32 2 2 33 2 3 34 2 4 35 2 6 36 2 8 37 2 12 38 2 16 39 2 2840 2 40 41 2 56 42-63 Reserved

2302. A terminal device receives the indication information sent by thenetwork device.

2303. The terminal device determines, based on the correspondence table,the modulation and coding scheme corresponding to the at least one MCSindex.

It should be understood that an implementation of this embodiment ofthis application may be similar to the implementation of the embodimentshown in FIG. 22. To avoid repetition, details are not described hereinagain.

Therefore, according to the communication method in this embodiment ofthis application, the network device determines the indicationinformation based on the correspondence table, where the indicationinformation is used to indicate the at least one channel qualityindicator MCS index, the correspondence table includes the N MCSindexes, the M modulation schemes, and the K code rate parameters, theat least one of the N MCS indexes corresponds to one type of modulationscheme, the K of the N MCS indexes are in a one-to-one correspondencewith the K code rate parameters, and the product of the code ratecorresponding to the first MCS index of the N MCS indexes and themodulation order of the modulation scheme corresponding to the first MCSindex is a value greater than 0 and less than 0.0781, where Code RateParameter=Code Rate×1024, N>M, N≥K, and N, K, and M are all positiveintegers; and the network device sends the indication information, sothat the terminal device determines, according to the indicationinformation, the modulation scheme corresponding to the at least one MCSindex. In other words, this application can be applied to a system thatrequires spectrum efficiency lower than 0.0781, that is, an area in abad channel condition is covered, to ensure that a user can performcommunication on a deep fading channel.

FIG. 24 is a schematic block diagram of a network device 2400 accordingto an embodiment of this application. As shown in FIG. 24, the networkdevice 2400 includes: a receiving module 2410, configured to receive achannel quality parameter that corresponds to each BLER in a first BLERsubset and that is sent by a terminal device, where the channel qualityparameter is used to indicate channel quality between the terminaldevice and the network device; and a processing module 2420, configuredto determine, based on at least one channel quality parameter differenceand a channel quality parameter corresponding to at least one BLER inthe first BLER subset, a channel quality parameter corresponding to atleast one BLER in a second BLER subset, where the at least one channelquality parameter difference includes a difference between the channelquality parameter corresponding to the at least one BLER in the secondBLER subset and the channel quality parameter corresponding to the atleast one BLER in the first BLER subset.

Optionally, the network device 2400 further includes a sending module,configured to send a channel quality parameter request to the terminaldevice, where the channel quality parameter request is used to requestat least one channel quality parameter difference between a channelquality parameter corresponding to at least one BLER in a second BLERsubset in a first BLER set and a channel quality parameter correspondingto at least one BLER in a first BLER subset in the first BLER set. Thereceiving module 2410 is further configured to receive the at least onechannel quality parameter difference between the channel qualityparameter corresponding to the at least one BLER in the second BLERsubset in the first BLER set and the channel quality parametercorresponding to the at least one BLER in the first BLER subset in thefirst BLER set.

Optionally, the network device 2400 further includes a sending module,configured to send a channel quality parameter request to the terminaldevice, where the channel quality parameter request is used to request achannel quality parameter difference between a channel quality parametercorresponding to at least one BLER in a second BLER subset in each of aat least one BLER set and a channel quality parameter corresponding toat least one BLER in a first BLER subset. The receiving module 2410 isfurther configured to receive the channel quality parameter differencebetween the channel quality parameter corresponding to the at least oneBLER in the second BLER subset in each of the at least one BLER set andthe channel quality parameter corresponding to the at least one BLER inthe first BLER subset.

Optionally, if the method is applied to a system that supports at leasttwo BLER sets, any two of the at least two BLER sets correspond todifferent transmission modes.

Optionally, the transmission modes include an antenna port configurationand/or a multiple-input multiple-output MIMO preprocessing mode.

Therefore, in this embodiment of this application, the network devicemay receive a channel quality parameter that corresponds to a BLER inthe first BLER subset in the first BLER set and that is sent by theterminal device, and determine, based on channel quality parameterscorresponding to some BLERs in the first BLER subset and the channelquality parameter difference between the channel quality parametercorresponding to each BLER in the second BLER subset and the channelquality parameter corresponding to the at least one BLER in the firstBLER subset, channel quality parameters corresponding to all BLERs inthe second BLER subset. In other words, the network device can determinechannel quality parameters corresponding to all BLERs in the first BLERset, and therefore the terminal device does not need to send the channelquality parameters corresponding to all the BLERs in the first BLER set,thereby reducing signaling overheads.

It should be understood that the network device 2400 in this embodimentof this application may correspond to the network device in the datatransmission method 2000 in the embodiments of this application, and theforegoing and other management operations and/or functions of themodules in the network device 2400 are separately used to implementcorresponding steps of the foregoing methods. For brevity, details arenot described herein again.

In this embodiment of this application, the receiving module 2410 may beimplemented by a transceiver, and the processing module 2420 may beimplemented by a processor. As shown in FIG. 25, a network device 2500may include a transceiver 2510, a processor 2520, and a memory 2530. Thememory 2530 may be configured to store indication information, and maybe further configured to store code, an instruction, and the likeexecuted by the processor 2520.

FIG. 26 is a schematic block diagram of a terminal device 2600 accordingto an embodiment of this application. As shown in FIG. 26, the terminaldevice 2600 is applied to a system that supports at least one blockerror rate BLER set, each of the at least one BLER set includes a firstBLER subset and a second BLER subset, the first BLER subset includes atleast one BLER, the second BLER subset includes at least one BLER, andthe terminal device 2600 includes: a processing module 2610, configuredto determine a channel quality parameter corresponding to each BLER inthe first BLER subset, where the channel quality parameter is used toindicate channel quality between the terminal device and a networkdevice; and a sending module 2620, configured to send the channelquality parameter corresponding to each BLER in the first BLER subset tothe network device, so that the network device determines, based on atleast one channel quality parameter difference and a channel qualityparameter corresponding to the at least one BLER in the first BLERsubset, a channel quality parameter corresponding to the at least oneBLER in the second BLER subset, where the at least one channel qualityparameter difference includes a difference between the channel qualityparameter corresponding to the at least one BLER in the second BLERsubset and the channel quality parameter corresponding to the at leastone BLER in the first BLER subset.

Optionally, the terminal device 2600 further includes a receivingmodule, configured to receive a channel quality parameter request sentby the network device, where the channel quality parameter request isused to request at least one channel quality parameter differencebetween a channel quality parameter corresponding to at least one BLERin a second BLER subset in a first BLER set and a channel qualityparameter corresponding to at least one BLER in a first BLER subset inthe first BLER set. The processing module 2610 is further configured tosend the at least one channel quality parameter difference between thechannel quality parameter corresponding to the at least one BLER in thesecond BLER subset in the first BLER set and the channel qualityparameter corresponding to the at least one BLER in the first BLERsubset in the first BLER set to the network device according to thechannel quality parameter request.

Optionally, the terminal device 2600 further includes a receivingmodule, configured to receive a channel quality parameter request sentby the network device, where the channel quality parameter request isused to request the channel quality parameter difference between thechannel quality parameter corresponding to the at least one BLER in thesecond BLER subset in each of the at least one BLER set and the channelquality parameter corresponding to the at least one BLER in the firstBLER subset. The processing module 2610 is further configured to sendthe channel quality parameter difference between the channel qualityparameter corresponding to the at least one BLER in the second BLERsubset in each of the at least one BLER set and the channel qualityparameter corresponding to the at least one BLER in the first BLERsubset to the network device according to the channel quality parameterrequest.

Optionally, if the method is applied to a system that supports at leasttwo BLER sets, any two of the at least two BLER sets correspond todifferent CQI levels.

Optionally, if the method is applied to a system that supports at leasttwo BLER sets, any two of the at least two BLER sets correspond todifferent transmission modes.

Optionally, the transmission modes include an antenna port configurationand/or a multiple-input multiple-output MIMO preprocessing mode.

Therefore, in this embodiment of this application, the terminal devicesends a channel quality parameter corresponding to each BLER in thefirst BLER subset in the first BLER set, and determines, based onchannel quality parameters corresponding to some BLERs in the first BLERsubset and the channel quality parameter difference between the channelquality parameter corresponding to each BLER in the second BLER subsetand the channel quality parameter corresponding to the at least one BLERin the first BLR subset, channel quality parameters corresponding to allBLERs in the second BLER subset. In other words, the network device candetermine channel quality parameters corresponding to all BLERs in thefirst BLER set, and therefore the terminal device does not need to sendthe channel quality parameters corresponding to all the BLERs in thefirst BLER set, thereby reducing signaling overheads.

It should be understood that the terminal device 2600 in this embodimentof this application may correspond to the terminal device in the datatransmission method 2000 in the embodiments of this application, and theforegoing and other management operations and/or functions of themodules in the terminal device 2600 are separately used to implementcorresponding steps of the foregoing methods. For brevity, details arenot described herein again.

In this embodiment of this application, the sending module 2620 may beimplemented by a transceiver, and the processing module 2610 may beimplemented by a processor. As shown in FIG. 27, a terminal device 2700may include a transceiver 2710, a processor 2720, and a memory 2730. Thememory 2730 may be configured to store indication information, and maybe further configured to store code, an instruction, and the likeexecuted by the processor 2720.

It should be understood that the processor 2520 or the processor 2720may be an integrated circuit chip and has a signal processingcapability. In an implementation process, steps of the foregoing methodembodiments may be completed by using a hardware integrated logiccircuit in the processor, or by using an instruction in a form ofsoftware. The processor may be a general purpose processor, a digitalsignal processor (Digital Signal Processor, DSP), anapplication-specific integrated circuit (Application Specific IntegratedCircuit, ASIC), a field programmable gate array (Field Programmable GateArray, FPGA) or another programmable logic device, a discrete gate ortransistor logic device, or a discrete hardware component. The processormay implement or perform the methods, the steps, and the logical blockdiagrams that are disclosed in the embodiments of the present invention.The general purpose processor may be a microprocessor, or the processormay be any conventional processor or the like. The steps of the methodsdisclosed with reference to the embodiments of the present invention maybe directly performed and completed by a hardware decoding processor, ormay be performed and completed by using a combination of hardware in thedecoding processor and a software module. The software module may belocated in a mature storage medium in the art, such as a random accessmemory, a flash memory, a read-only memory, a programmable read-onlymemory, an electrically erasable programmable memory, or a register. Thestorage medium is located in the memory, and the processor readsinformation in the memory and completes the steps of the foregoingmethods in combination with hardware in the processor.

It may be understood that the memory 2530 or the memory 2730 in theembodiments of the present invention may be a volatile memory or anonvolatile memory, or may include both a volatile memory and anonvolatile memory. The nonvolatile memory may be a read-only memory(ROM), a programmable read-only memory (PROM), an erasable programmableread-only memory (EPROM), an electrically erasable programmableread-only memory (EEPROM), or a flash memory. The volatile memory may bea random access memory (RAM) and is used as an external cache. By way ofexample rather than limitation, many forms of RAMs may be used, and are,for example, a static random access memory (SRAM), a dynamic randomaccess memory (DRAM), a synchronous dynamic random access memory(SDRAM), a double data rate synchronous dynamic random access memory(DDR SDRAM), an enhanced synchronous dynamic random access memory(ESDRAM), a synchronous link dynamic random access memory (SLDRAM), anda direct rambus random access memory (DR RAM).

It should be noted that the memory in the systems and the methodsdescribed in this specification includes but is not limited to thesememories and a memory of any other appropriate type.

An embodiment of this application further provides a system chip, wherethe system chip includes an input/output interface, at least oneprocessor, at least one memory, and a bus. The at least one memory isconfigured to store an instruction, and the at least one processor isconfigured to invoke the instruction of the at least one memory toperform operations in the methods in the foregoing embodiments.

FIG. 28 shows a resource allocation system 2800 according to anembodiment of this application. The system 2800 includes: the networkdevice 2400 in the embodiment shown in FIG. 24 and the terminal device2600 in the embodiment shown in FIG. 26.

An embodiment of this application further provides a computer storagemedium, where the computer storage medium may store a programinstruction for performing any of the foregoing methods.

Optionally, the storage medium may be specifically the memory 2530 orthe memory 2730.

FIG. 29 is a schematic block diagram of a terminal device 2900 accordingto an embodiment of this application. As shown in FIG. 29, the terminaldevice 2900 includes: a processing module 2910, configured to determineindication information based on a correspondence table, where theindication information is used to indicate at least one channel qualityindicator CQI index, the correspondence table includes N CQI indexes, Mmodulation schemes, and K code rate parameters, at least one of the NCQI indexes corresponds to one type of modulation scheme, K of the N CQIindexes are in a one-to-one correspondence with the K code rateparameters, and a product of a code rate corresponding to a first CQIindex of the N CQI indexes and a modulation order of a modulation schemecorresponding to the first CQI index is a value greater than 0 and lessthan 0.0781, where Code Rate Parameter=Code Rate×1024, N>M, N≥K, and N,K, and M are all positive integers; and a sending module 2920,configured to send the indication information to a network device.

Optionally, the K code rate parameters include a value greater than 0and less than 40.

Optionally, the N CQI indexes in the correspondence table are arrangedin ascending order, products of modulation orders of modulation schemescorresponding to all of the first P CQI indexes of the N CQI indexes andcode rates corresponding to all of the first P CQI indexes are arrangedin ascending order, and a product of a modulation order of a modulationscheme corresponding to a (P+h)^(th) CQI index and a code ratecorresponding to the (P+h)^(th) CQI index is less than a product of amodulation order of a modulation scheme corresponding to a P^(th) CQIindex and a code rate corresponding to the P^(th) CQI index, whereN>P+h, h is a value ranging from 1 to N−X, and X>P.

Therefore, in this embodiment of this application, the terminal devicedetermines the indication information based on the correspondence table,where the indication information is used to indicate the at least onechannel quality indicator CQI index, the correspondence table includesthe N CQI indexes, the M modulation schemes, and the K code rateparameters, the at least one of the N CQI indexes corresponds to onetype of modulation scheme, the K of the N CQI indexes are in aone-to-one correspondence with the K code rate parameters, and theproduct of the code rate corresponding to the first CQI index of the NCQI indexes and the modulation order of the modulation schemecorresponding to the first CQI index is a value greater than 0 and lessthan 0.0781, where Code Rate Parameter=Code Rate×1024, N>M, N≥K, and N,K, and M are all positive integers; and the terminal device sends theindication information, so that the network device determines, accordingto the indication information, the modulation scheme corresponding tothe at least one CQI index. In other words, this application can beapplied to a system that requires spectrum efficiency lower than 0.0781,that is, an area in a bad channel condition is covered, to ensure that auser can perform communication on a deep fading channel.

It should be understood that the terminal device 2900 in this embodimentof this application may correspond to the terminal device in thecommunication method in the embodiments of this application, and theforegoing and other management operations and/or functions of themodules in the terminal device 2900 are separately used to implementcorresponding steps of the foregoing methods. For brevity, details arenot described herein again.

In this embodiment of this application, the sending module 2920 may beimplemented by a transceiver, and the processing module 2910 may beimplemented by a processor. As shown in FIG. 30, a terminal device 3000may include a transceiver 3010, a processor 3020, and a memory 3030. Thememory 3030 may be configured to store indication information, and maybe further configured to store code, an instruction, and the likeexecuted by the processor 3020.

FIG. 31 is a schematic block diagram of a network device 3100 accordingto an embodiment of this application. As shown in FIG. 31, the networkdevice 3100 includes: a receiving module 3110, configured to receiveindication information, where the indication information is used toindicate at least one channel quality indicator CQI index; and aprocessing module 3120, configured to determine, based on acorrespondence table, a modulation and coding scheme corresponding tothe at least one CQI index, where the correspondence table includes NCQI indexes, M modulation schemes, and K code rate parameters, at leastone of the N CQI indexes corresponds to one type of modulation scheme, Kof the N CQI indexes are in a one-to-one correspondence with the K coderate parameters, and a product of a code rate parameter corresponding toa first CQI index of the N CQI indexes and a modulation order of amodulation scheme corresponding to the first CQI index is a valuegreater than 0 and less than 0.0781, where Code Rate Parameter=CodeRate×1024, N>M, N≥K, and N, K, and M are all positive integers.

Optionally, the K code rate parameters include a value greater than 0and less than 40.

Optionally, the N CQI indexes in the correspondence table are arrangedin ascending order, products of modulation orders of modulation schemescorresponding to all of the first P CQI indexes of the N CQI indexes andcode rate parameters corresponding to all of the first P CQI indexes arearranged in ascending order, and a product of a modulation order of amodulation scheme corresponding to a (P+h)^(th) CQI index and a coderate parameter corresponding to the (P+h)^(th) CQI index is less than aproduct of a modulation order of a modulation scheme corresponding to aP^(th) CQI index and a code rate parameter corresponding to the P^(th)CQI index, where N>P+h, h is a value ranging from 1 to N−X, and X>P.

Therefore, in this embodiment of this application, the network devicereceives the indication information, and determines, based on thecorrespondence table, the modulation scheme corresponding to the atleast one CQI index, where the correspondence table includes the N CQIindexes, the M modulation schemes, and the K code rate parameters, theat least one of the N CQI indexes corresponds to one type of modulationscheme, the K of the N CQI indexes are in a one-to-one correspondencewith the K code rate parameters, and the product of the code ratecorresponding to the first CQI index of the N CQI indexes and themodulation order of the modulation scheme corresponding to the first CQIindex is a value greater than 0 and less than 0.0781, where Code RateParameter=Code Rate×1024, N>M, N≥K, and N, K, and M are all positiveintegers; and the network device sends the indication information, sothat the network device determines, according to the indicationinformation, the modulation scheme corresponding to the at least one CQIindex. In other words, this application can be applied to a system thatrequires spectrum efficiency lower than 0.0781, that is, an area in abad channel condition is covered, to ensure that a user can performcommunication on a deep fading channel.

It should be understood that the network device 3100 in this embodimentof this application may correspond to the network device in thecommunication method in the embodiments of this application, and theforegoing and other management operations and/or functions of themodules in the network device 3100 are separately used to implementcorresponding steps of the foregoing methods. For brevity, details arenot described herein again.

In this embodiment of this application, the receiving module 3110 may beimplemented by a transceiver, and the processing module 3120 may beimplemented by a processor. As shown in FIG. 32, a network device 3200may include a transceiver 3210, a processor 3220, and a memory 3230. Thememory 3230 may be configured to store indication information, and maybe further configured to store code, an instruction, and the likeexecuted by the processor 3220.

It should be understood that the processor 3020 or the processor 3220may be an integrated circuit chip and has a signal processingcapability. In an implementation process, steps of the foregoing methodembodiments may be completed by using a hardware integrated logiccircuit in the processor, or by using an instruction in a form ofsoftware. The processor may be a general purpose processor, a digitalsignal processor (Digital Signal Processor, DSP), anapplication-specific integrated circuit (Application Specific IntegratedCircuit, ASIC), a field programmable gate array (Field Programmable GateArray, FPGA) or another programmable logic device, a discrete gate ortransistor logic device, or a discrete hardware component. The processormay implement or perform the methods, the steps, and the logical blockdiagrams that are disclosed in the embodiments of the present invention.The general purpose processor may be a microprocessor, or the processormay be any conventional processor or the like. The steps of the methodsdisclosed with reference to the embodiments of the present invention maybe directly performed and completed by a hardware decoding processor, ormay be performed and completed by using a combination of hardware in thedecoding processor and a software module. The software module may belocated in a mature storage medium in the art, such as a random accessmemory, a flash memory, a read-only memory, a programmable read-onlymemory, an electrically erasable programmable memory, or a register. Thestorage medium is located in the memory, and the processor readsinformation in the memory and completes the steps of the foregoingmethods in combination with hardware in the processor.

It may be understood that the memory 3030 or the memory 3230 in theembodiments of the present invention may be a volatile memory or anonvolatile memory, or may include both a volatile memory and anonvolatile memory. The nonvolatile memory may be a read-only memory(ROM), a programmable read-only memory (PROM), an erasable programmableread-only memory (EPROM), an electrically erasable programmableread-only memory (EEPROM), or a flash memory. The volatile memory may bea random access memory (RAM) and is used as an external cache. By way ofexample rather than limitation, many forms of RAMs may be used, and are,for example, a static random access memory (SRAM), a dynamic randomaccess memory (DRAM), a synchronous dynamic random access memory(SDRAM), a double data rate synchronous dynamic random access memory(DDR SDRAM), an enhanced synchronous dynamic random access memory(ESDRAM), a synchronous link dynamic random access memory (SLDRAM), anda direct rambus random access memory (DR RAM).

It should be noted that the memory in the systems and the methodsdescribed in this specification includes but is not limited to thesememories and a memory of any other appropriate type.

An embodiment of this application further provides a system chip, wherethe system chip includes an input/output interface, at least oneprocessor, at least one memory, and a bus. The at least one memory isconfigured to store an instruction, and the at least one processor isconfigured to invoke the instruction of the at least one memory toperform operations in the methods in the foregoing embodiments.

FIG. 33 shows a resource allocation system 3300 according to anembodiment of this application. The system 3300 includes: the networkdevice 2900 in the embodiment shown in FIG. 29 and the terminal device3100 in the embodiment shown in FIG. 31.

An embodiment of this application further provides a computer storagemedium, where the computer storage medium may store a programinstruction for performing any of the foregoing methods.

Optionally, the storage medium may be specifically the memory 3030 orthe memory 3230.

A person of ordinary skill in the art may be aware that, in combinationwith the examples described in the embodiments disclosed in thisspecification, units and algorithm steps can be implemented byelectronic hardware or a combination of computer software and electronichardware. Whether the functions are performed by hardware or softwaredepends on particular applications and design constraints of thetechnical solutions. A person skilled in the art may use differentmethods to implement the described functions for each particularapplication, but it should not be considered that the implementationgoes beyond the scope of this application.

It may be clearly understood by a person skilled in the art that, forthe purpose of convenient and brief description, for a detailed workingprocess of the foregoing system, apparatus, and unit, refer to acorresponding process in the foregoing method embodiment. Details arenot described herein again.

In the several embodiments provided in this application, it should beunderstood that the disclosed system, apparatus, and method may beimplemented in other manners. For example, the described apparatusembodiment is merely an example. For example, the unit division ismerely logical function division and may be other division in actualimplementation. For example, a plurality of units or components may becombined or integrated into another system, or some features may beignored or not performed. In addition, the displayed or discussed mutualcouplings or direct couplings or communication connections may beimplemented through some interfaces. The indirect couplings orcommunication connections between the apparatuses or units may beimplemented in electronic, mechanical, or other forms.

The units described as separate parts may be or may not be physicallyseparate, and parts displayed as units may be or may not be physicalunits, may be located in one position, or may be distributed on aplurality of network units. Some or all of the units may be selectedbased on actual requirements to achieve the objectives of the solutionsof the embodiments.

In addition, functional units in the embodiments of this application maybe integrated into one processing unit, or each of the units may existalone physically, or two or more units are integrated into one unit.

When the functions are implemented in a form of a software functionalunit and sold or used as an independent product, the functions may bestored in a computer readable storage medium. Based on such anunderstanding, the technical solutions in this application essentially,or the part contributing to the current system, or some of the technicalsolutions may be implemented in a form of a software product. Thecomputer software product is stored in a storage medium, and includesseveral instructions for instructing a computer device (which may be apersonal computer, a server, a network device, or the like) to performall or some of the steps of the methods described in the embodiments ofthis application. The foregoing storage medium includes: any medium thatcan store program code, such as a USB flash drive, a removable harddisk, a read-only memory (ROM), a random access memory (RAM), a magneticdisk, or an optical disc.

The foregoing descriptions are merely specific implementations of thisapplication, but are not intended to limit the protection scope of thisapplication. Any variation or replacement readily figured out by aperson skilled in the art within the technical scope disclosed in thisapplication shall fall within the protection scope of this application.Therefore, the protection scope of this application shall be subject tothe protection scope of the claims.

What is claimed is:
 1. A method, comprising: determining, by a device,indication information according to a correspondence table, wherein theindication information indicates at least one modulation and codingscheme (MCS) index, the correspondence table comprises: N MCS indexes,at least one of the N MCS indexes corresponds to a first type ofmodulation scheme; M modulation schemes; and K code rate parameters, Kof the N MCS indexes are in a one-to-one correspondence with the K coderate parameters, and a product of a code rate corresponding to a firstMCS index of the N MCS indexes and a modulation order of a modulationscheme corresponding to the first MCS index is a value greater than 0and less than 0.0781, wherein a code rate parameter is a product of acode rate and 1024, N>M, N≥K, and N, K, and M are all positive integers;and sending, by the device, the indication information.
 2. The methodaccording to claim 1, wherein the K code rate parameters comprise avalue greater than 0 and less than
 40. 3. A method, comprising:receiving, by a device, indication information, wherein the indicationinformation indicates at least one modulation and coding scheme (MCS)index; and determining, according to a correspondence table, amodulation and coding scheme corresponding to the at least one MCSindex, wherein the correspondence table comprises: N MCS indexes, atleast one of the N MCS indexes corresponds to one type of modulationscheme; M modulation schemes; and K code rate parameters, K of the N MCSindexes are in a one-to-one correspondence with the K code rateparameters, and a product of a code rate parameter corresponding to afirst MCS index of the N MCS indexes and a modulation order of amodulation scheme corresponding to the first MCS index is a valuegreater than 0 and less than 0.0781, wherein a code rate parameter is aproduct of a code rate and 1024, N>M, N≥K, and N, K, and M are allpositive integers.
 4. The method according to claim 3, wherein the Kcode rate parameters comprise a value greater than 0 and less than 40.5. An apparatus, comprising: a transceiver; at least one processor; anda non-transitory computer-readable storage medium coupled to the atleast one processor and storing programming instructions for executionby the at least one processor, wherein the programming instructionsinstruct: the at least one processor to determine indication informationaccording to a correspondence table, wherein the indication informationindicates at least one modulation and coding scheme (MCS) index, and thecorrespondence table comprises: N MCS indexes, at least one of the N MCSindexes corresponds to one type of modulation scheme; M modulationschemes; and K code rate parameters, K of the N MCS indexes are in aone-to-one correspondence with the K code rate parameters, and a productof a code rate corresponding to a first MCS index of the N MCS indexesand a modulation order of a modulation scheme corresponding to the firstMCS index is a value greater than 0 and less than 0.0781, wherein a coderate parameter is a product of a code rate and 1024, N>M, N≥K, and N, K,and M are all positive integers; and the transceiver to send theindication information.
 6. The apparatus according to claim 5, whereinthe K code rate parameters comprise a value greater than 0 and less than40.
 7. A communications apparatus, comprising: a transceiver; at leastone processor; and a non-transitory computer-readable storage mediumcoupled to the at least one processor and storing programminginstructions for execution by the at least one processor, wherein theprogramming instructions instruct: the transceiver to receive indicationinformation, wherein the indication information indicates at least onemodulation and coding scheme (MCS) index; and the at least one processorto determine, according to a correspondence table, a modulation andcoding scheme corresponding to the at least one MCS index, wherein thecorrespondence table comprises: N MCS indexes, at least one of the N MCSindexes corresponds to one type of modulation scheme; M modulationschemes; and K code rate parameters K of the N MCS indexes are in aone-to-one correspondence with the K code rate parameters, and a productof a code rate parameter corresponding to a first MCS index of the N MCSindexes and a modulation order of a modulation scheme corresponding tothe first MCS index is a value greater than 0 and less than 0.0781,wherein a code rate parameter is a product of a code rate and 1024, N>M,N≥K, and N, K, and M are all positive integers.
 8. The communicationsapparatus according to claim 7, wherein the K code rate parameterscomprise a value greater than 0 and less than
 40. 9. A non-transitorycomputer-readable storage medium storing programming instructions for:determining indication information according to a correspondence table,wherein the indication information indicates at least one modulation andcoding scheme (MCS) index, the correspondence table comprises: N MCSindexes, at least one of the N MCS indexes corresponds to one type ofmodulation scheme; M modulation schemes; and K code rate parameters, Kof the N MCS indexes are in a one-to-one correspondence with the K coderate parameters, and a product of a code rate corresponding to a firstMCS index of the N MCS indexes and a modulation order of a modulationscheme corresponding to the first MCS index is a value greater than 0and less than 0.0781, wherein a code rate parameter is a product of acode rate and 1024, N>M, N≥K, and N, K, and M are all positive integers;and sending the indication information.
 10. The non-transitorycomputer-readable storage medium according to claim 9, wherein the Kcode rate parameters comprise a value greater than 0 and less than 40.